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FLYING MACHINES TODAY 



"Hitherto aviation has been almost monopolized by that much-over- 
praised and much-overtrusted person, ' the practical man.' It is much in 
need of the services of the theorist — the engineer with his mathematical 
calculations of how a flying machine ought to be built and of how the 
material used in its construction should be distributed to give the greatest 
possible amount of strength and efficiency." 

— From the New York Times, January 16, 191 1. 



FLYING MACH INES 
TODAY 



BY 
WILLIAM DUANE ENNIS 

Professor of Mechanical Engineering in the Polytechnic 
Institute of Brooklyn 



123 ILLUSTRATIONS 




NEW YORK 
D. VAN NOSTRAND COMPANY 

23 Murray and i 9 i i 27 Warren Sts. 



Copyright, ign, by 
D. Van Nostrand Company 



x 



THE • PLIMPTON • PRESS ■ NORWOOD • MASS • U • S • A 



©CI.A295199 



MY MOTHER 



PREFACE 

Speaking with some experience, the writer has found 
that instruction in the principles underlying the science 
and sport of aviation must be vitalized by some contem- 
poraneous study of what is being accomplished in the air. 
No one of the revolutionizing inventions of man has pro- 
gressed as rapidly as aerial navigation. The " truths" of 
today are the absurdities of tomorrow. 

The suggestion that some grasp of the principles and a 
very fair knowledge of the current practices in aeronautics 
may be had without special technical knowledge came 
almost automatically. If this book is comprehensible to 
the lay reader, and if it conveys to him even a small pro- 
portion of the writer's conviction that flying machines are 
to profoundly influence our living in the next generation, 
it will have accomplished its author's purpose. 



Polytechnic Institute of Brooklyn, 
New York, April, 191 1. 



CONTENTS 

PAGE 

THE DELIGHTS AND DANGERS OF FLYING. — Dangers 

of Aviation. — What it is Like to Fly i 

SOARING FLIGHT BY MAN.— What Holds it Up?— Lift- 
ing Power. — Why so Many Sails? — Steering ... 17 

TURNING CORNERS. — What Happens when Making a 
Turn. — Lateral Stability. — Wing Warping. — Auto- 
matic Control. — The Gyroscope. — Wind Gusts. . . 33 

AIR AND THE WIND. — Sailing Balloons. — Field and 

Speed 43 

GAS AND BALLAST. — Buoyancy in Air. — Ascending and 

Descending. — The Ballonet. — The Equtlibrator . . 57 

DIRIGIBLE BALLOONS AND OTHER KINDS.— Shapes- 
Dimensions. — Fabrics. — Framing. — Keeping the Keel 
Horizontal. — Stability. — Rudders and Planes. — Arrange- 
ment and Accessories. — Amateur Dirigibles. — The Fort 
Omaha Plant. — Balloon Progress 71 

THE QUESTION OF POWER. — Resistance of Aeroplanes. — 
Resistance of Dirigibles. — Independent Speed and 
Time-Table. — The Cost of Speed. — The Propeller . 101 

GETTING UP AND DOWN; MODELS AND GLIDERS; 
AEROPLANE DETAILS. —Launching. — Descending — 
Gliders. — Models. — Balancing. — Weights. — Miscel- 
laneous. — Things to Look After 121 

SOME AEROPLANES. — SOME ACCOMPLISHMENTS . . 143 

THE POSSIBILITIES IN AVIATION. — The Case of the 
Dirigible. — The Orthopter. — The Helicopter. — Com- 
posite Types. — What is Promised 170 

AERIAL WARFARE .189 



LIST OF ILLUSTRATIONS 



PAGE 

The Fall of Icarus Frontispiece 

The Aviator " . 3 

The Santos-Dumont "Demoiselle" 4 

View from a Balloon 9 

Anatomy of a Bird's Wing 10 

Flight of a Bird 11 

In a Meteoric Shower 13 

How a Boat Tacks 15 

Octave Chanute 18 

Pressure of the Wind 10 

Forces Acting on a Kite 20 

Sustaining Force in the Aeroplane 23 

Direct Lifting and Resisting Forces 24 

Shapes of Planes 26 

Balancing Sail ' 28 

Roe's Triplane at Wembley 30 

Action of the Steering Rudder 31 

Recent Type of Wright Biplane 31 

Circular Flight v ^^ 

The Aileron 35 

Wing Tipping 36 

Wing Warping 37 

The Gyroscope 39 

Diurnal Temperatures at Different Heights 45 

Seasonal Variation in Wind Velocities 47 

The Wind Rose for Mt. Weather, Va 49 

Diagram of Parts of a Drifting Balloon 51 

Glidden and Stevens Getting Away in the "Boston" .... 52 

Relative and Absolute Balloon Velocities 53 

Field and Speed 53 

Influence of Wind on Possible Course 54 

Count Zeppelin 55 

Buoyant Power of Wood 57 

One Cubic Foot of Wood Loaded in Water 58 

xiii 



xiv List of Illustrations 

PAGE 

Buoyant Power of Hydrogen 59 

Lebaudy's " Jaune" 60 

Air Balloon 62 

Screw Propeller for Altitude Control 66 

Balloon with Ballonets 67 

Construction of the Zeppelin Balloon 68 

The Equilibrator 69 

Henry Giffard's Dirigible 71 

Dirigible of Dupuy de Lome 72 

Tissandier Brothers' Dirigible Balloon 73 

The "Baldwin" 74 

The "Zeppelin" on Lake Constance 75 

The "Patrie" 77 

Manufacturing the Envelope of a Balloon 79 

Andree's Balloon, " L'Oernen" 80 

Wreck of the "Zeppelin" 82 

Car of the "Zeppelin" 84 

Stern View of the " Zeppelin " 86 

The "Clement-Bayard" 87 

The "Villede Paris" 88 

Car of the "Liberie" 89 

The "Zodiac No. 2" 92 

United States Signal Corps Balloon Plant at Fort Omaha . . 93 

The "Caroline" 94 

The Ascent at Versailles, 1783 95 

Proposed Dirigible 96 

The " Re publique" 97 

The First Flight for the Gordon-Bennett Cup 99 

The Gnome Motor 102 

Screw Propeller io 3 

One of the Motors of the "Zeppelin" 104 

The Four-Cycle Engine IO S 

Action of Two-Cycle Engine 106 

Motor and Propeller IQ 8 

Two-Cylinder Opposed Engine no 

Four-Cylinder Vertical Engine no 

Head End Shapes n 3 

The Santos-Dumont Dirigible No. 2 115 

In the Bay of Monaco: Santos-Dumont n 7 

Wright Biplane on Starting Rail • ■ 121 

Launching System for Wright Aeroplane 122 



List of Illustrations xv 

PAGE 

The Xieuport Monoplane 124 

A Biplane 125 

Ely at Los Angeles 126 

Trajectory During Descent 127 

Descending ... 128 

The Witteman Glider 130 

French Monoplane 132 

A Problem in Steering 133 

Lejeune Biplane 134 

Tellier Monoplane 135 

A Monoplane 137 

Cars and Framework 139 

Some Details 139 

Recent French Machines 141 

Orville Wright at Fort Myer 143 

The First Flight Across the Channel 144 

Wright Motor 145 

Voisin-Farman Biplane 147 

The Champagne Grand Prize Flight 148 

Farman's First Biplane 149 

The "June Bug" 150 

Curtiss Biplane 151 

Curtiss' Hydro- Aeroplane at San Diego Bay 152 

Flying Over the Water 153 

Bleriot-Voisin Cellular Biplane with Pontoons 154 

Latham's "Antoinette'''' 155 

James J. Ward at Lewiston Fair 156 

Marcel Penot in the U M ohawk" 157 

Santos-Dumont's "Demoiselle" 159 

Bleriot Monoplane 160 

Latham's Fall into the Channel 161 

De Lesseps Crossing the Channel 163 

The Maxim Aeroplane 164 

Langley's Aeroplane 165 

Robart Monoplane 166 

Vina Monoplane 167 

Blanc Monoplane 17° 

Melvin Vaniman Triplane 17 1 

Jean de Crawhez Triplane 17 1 

A Triplane 17 2 

Giraudon's Wheel Aeroplane 175 



xvi List of Illustrations 

PAGE 

Breguet Gyroplane (Helicopter) 177 

Wellman's "America" 181 

The German Emperor Watching the Progress of Aviation . . . 189 

Automatic Gun for Attacking Airships 193 

Gun for Shooting at Aeroplanes 197 

Santos-Dumont Circling the Eiffel Tower 199 

Latham, Farman and Paulhan 202 



FLYING MACHINES TODAY 



THE DELIGHTS AND DANGERS OF FLYING 

Few things have more charm for man than flight. The 
soaring of a bird is beautiful and the gliding of a yacht 
before the wind has something of the same beauty. The 
child's swing; the exercise of skating on good ice; a sixty- 
mile-an-hour spurt on a smooth road in a motor car; even 
the slightly passe bicycle: these things have all in their 
time appealed to us because they produce the illusion of 
flight — of progress through the intangible air with all 
but separation from the prosaic earth. 

But these sensations have been only illusions. To actu- 
ally leave the earth and wander at will in aerial space — 
this has been, scarcely a hope, perhaps rarely even a dis- 
tinct dream. From the days of Daedalus and Icarus, of 
Oriental flying horses and magic carpets, down to " Darius 
Green and his flying machine," free flight and frenzy were 
not far apart. We were learnedly told, only a few years 
since, that sustention by heavier-than-air machines was 
impossible without the discovery, first, of some new 
matter or some new force. It is now (191 1) only eight 
years since Wilbur Wright at Kitty Hawk, with the aid of 
the new (?) matter — aluminum — and the "new" force — 
the gasoline engine — in three successive flights proved 
that a man could travel through the air and safely descend, 



2 Flying Machines Today 

in a machine weighing many times as much as the air it 
displaced. It is only five years since two designers — 
Surcouf and Lebaudy — built dirigible balloons approxi- 
mating present forms, the Ville de Paris and La Patrie. 
It is only now that we average people may confidently 
contemplate the prospect of an aerial voyage for ourselves 
before we die. A contemplation not without its shudder, 
perhaps; but yet not altogether more daring than that of 
our grandsires who first rode on steel rails behind a steam 
locomotive. 

The Dangers oe Aviation 

We are very sure to be informed of the fact when an 
aviator is killed. Comparatively little stir is made now- 
adays over an automobile fatality, and the ordinary rail- 
road accident receives bare mention. For instruction and 
warning, accidents to air craft cannot be given too much 
publicity; but if we wish any accurate conception of 
the danger we must pay regard to factors of proportion. 
There are perhaps a thousand aeroplanes and about 
sixty dirigible balloons in the world. About 500 men — 
amateurs and professionals — are continuously engaged 
in aviation. The Aero Club of France has issued in 
that country nearly 300 licenses. In the United States, 
licenses are held by about thirty individuals. We can 
form no intelligent estimate as to the number of un- 
licensed amateurs of all ages who are constantly experi- 
menting with gliders at more or less peril to life and limb. 

A French authority has ascertained the death rate 



The Delights and Dangers of Flying 3 

among air-men to have been — to date — about 6%. 
This is equivalent to about one life for 4000 miles of flight : 
but we must remember that accidents will vary rather 
with the number of ascents and descents than with the 
mileage. Four thousand miles in 100 flights would be 




much less perilous, under present conditions, than 4000 
miles in 1000 flights. 

There were 26 fatal aeroplane accidents between Sep- 
tember 17, 1908, and December 3, 19 10. Yet in that 
period there were many thousands of ascents: 1300 were 
made in one week at the Rheims tournament alone. Of 



4 Flying Machines Today 

the 26 accidents, 1 was due to a wind squall, 3 to collision, 
6 (apparently) to confusion of the aviator, and 12 to me- 
chanical breakage. An analysis of 40 British accidents 
shows 13 to have been due to engine failures, 10 to alighting 
on bad ground, 6 to wind gusts, 5 to breakage of the 
propeller, and 6 to fire and miscellaneous causes. These 




The Santos-Dumont "Demoiselle" 
(From The Aeroplane, by Hubbard, Ledeboer and Turner) 



casualties were not all fatal, although the percentage of 
fatalities in aeronautic accidents is high. The most serious 
results were those due to alighting on bad ground; long 
grass and standing grain being very likely to trip the 
machine and throw the occupant. French aviators are 
now strapping themselves to their seats in order to avoid 
this last danger. 



The Delights and Dangers of Flying 5 

Practically all of the accidents occur to those who are 
flying; but spectators may endanger themselves. Dur- 
ing one of the flights of Mauvais at Madrid, in March 
of the present year, the bystanders rushed through the 
barriers and out on the field before the machine had well 
started. A woman was decapitated by the propeller, 
and four other persons were seriously injured. 

Nearly all accidents result from one of three causes: bad 
design, inferior mechanical construction, and the taking of 
unnecessary risks by the operator. Scientific design at 
the present writing is perhaps impossible. Our knowledge 
of the laws of air resistance and sustention is neither 
accurate nor complete. Much additional study and experi- 
ment must be carried on; and some better method of experi- 
menting must be devised than that which sends a man up 
in the air and waits to see what happens. A thorough 
scientific analysis will not only make aviation safer, it will 
aid toward making it commercially important. Further 
data on propeller proportions and efficiencies, and on 
strains in the material of screws under aerial conditions 
will do much to standardize power plant equipment. The 
excessive number of engine breakdowns is obviously related 
to the extremely light weight of the engines employed: 
better design may actually increase these weights over 
those customary at present. Great weight reduction is no 
longer regarded as essential at present speeds in aerial 
navigation: we have perhaps already gone too far in this 
respect. 



6 Flying Machines Today 

Bad workmanship has been more or less unavoidable, 
since no one has yet had ten years' experience in building 
aeroplanes. The men who have developed the art have 
usually been sportsmen rather than mechanics, and only 
time is necessary to show the impropriety of using "safety 
pins" and bent wire nails for connections. 

The taking of risks has been an essential feature. When 
one man earns $100,000 in a year by dare-devil flights, 
when the public flocks in hordes — and pays good prices — 
to see a man risk his neck, he will usually aim to satisfy 
it. This is not developing aerial navigation: this is cir- 
cus riding — looping-the-loop performances which appeal 
to some savage instinct in us but lead us nowhere. Men 
have climbed two miles into the clouds, for no good pur- 
pose whatever. All that we need to know of high altitude 
conditions is already known or may be learned by ascents 
in anchored balloons. Records up to heights of sixteen 
miles have been obtained by sounding balloons. 

If these high altitudes may under certain conditions be 
desirable for particular types of balloon, they are essentially 
undesirable for the aeroplane. The supporting power of a 
heavier-than-air machine decreases in precisely inverse 
ratio with the altitude. To fly high will then involve 
either more supporting surface and therefore a structuially 
weaker machine, or greater speed and consequently a larger 
motor. It is true that the resistance to propulsion 
decreases at high altitudes, just as the supporting power 
decreases: and on this account, given only a sufficient 



The Delights and Dangers of Flying 7 

margin of supporting power, we might expect a standard 
machine to work about as well at a two-mile elevation as 
at a height of 200 feet; but rarefaction of the air at the 
higher altitudes decreases the weight of carbureted mix- 
ture drawn into the motor, and consequently its output. 
Any air-man who attempts to reach great heights in a 
machine not built for such purpose is courting disaster. 

Flights over cities, spectacular as they are, and popular as 
they are likely to remain, are doubly dangerous on account 
of the irregular air currents and absence of safe landing 
places. They have at last been officially discountenanced 
as not likely to advance the sport. 

All flights are exhibition flights. The day of a quiet, 
mind-your-own-business type of aerial journey has not 
yet arrived. Exhibition performances of any sort are 
generally hazardous. There were nine men killed in one 
recent automobile meet. If the automobile were used 
exclusively for races and contests, the percentage of fatali- 
ties might easily exceed that in aviation. It is claimed that 
no inexperienced aviator has ever been killed. This may 
not be true, but there is no doubt that the larger number 
of accidents has occurred to the better-known men from 
whom the public expects something daring. 

Probably the best summing up of the danger of aviation 
may be obtained from the insurance companies. The 
courts have decided that an individual does not forfeit 
his life insurance by making an occasional balloon trip. 
Regular classified rates for aeroplane and balloon operators 



8 Flying Machines Today 

are in force in France and Germany. It is reported that 
Mr. Grahame- White carries a life insurance policy at 35% 
premium — about the same rate as that paid by a " crowned 
head." Another aviator of a less professional type has 
been refused insurance even at 40% premium. Policies 
of insurance may be obtained covering damage to ma- 
chines by fire or during transportation and by collisions 
with other machines; and covering liability for injuries to 
persons other than the aviator. 

On the whole, flying is an ultra-hazardous occupation; 
but an occasional flight by a competent person or by a 
passenger with a careful pilot is simply a thrilling experi- 
ence, practically no more dangerous than many things 
we do without hesitation. Nearly all accidents have been 
due to preventable causes; and it is simply a matter of 
science, skill, perseverance, and determination to make an 
aerial excursion under proper conditions as safe as a journey 
in a motor car. Men who for valuable prizes undertake 
spectacular feats will be killed as frequently in aviation as 
in bicycle or even in automobile racing; but probably not 
very much more frequently, after design and workmanship 
in flying machines shall have been perfected. The total 
number of deaths in aviation up to February 9, 191 1, is 
stated to have been forty-two. 

What It Is Like to Fly 

We are fond of comparing flying machines with birds, 
with fish, and with ships: and there are useful analogies 






io Flying Machines Today 

with all three. A drifting balloon is like a becalmed ship 
or a dead fish. It moves at the speed of the aerial fluid 
about, it and the occupants perceive no movement what- 
ever. The earth's surface below appears to move in the 
opposite direction to that in which the wind carries the 
balloon. With a dirigible balloon or flying machine, the 
sensation is that of being exposed to a violent wind, against 
which (by observation of landmarks) we find that we 




Anatomy of a Bird's Wing 
(From Walker's Aerial Navigation) 

progress. It is the same experience as that obtained when 
standing in an exposed position on a steamship, and we 
wonder if a bird or a fish gradually gets so accustomed to 
the opposing current as to be unconscious of it. But in 
spite of jar of motors and machinery, there is a freedom of 
movement, a detachment from earth-associations, in air 
flight, that distinguishes it absolutely from the churning 
of a powerful vessel through the waves. 

Birds fly in one of three ways. The most familiar bird 



12 Flying Machines Today 

flight is by a rapid wing movement which has been called 
oar-like, but which is precisely equivalent to the usual 
movement of the arms of a man in swimming. The edge 
of the wing moves forward, cutting the air; on the return 
stroke the leading edge is depressed so as to present a 
nearly flat surface to the air and thus propel the bird for- 
ward. A slight downward direction of this stroke serves 
to impel the flight sufficiently upward to offset the effect 
of gravity. Any man can learn to swim, but no man can 
fly, because neither in his muscular frame nor by any device 
which he can attach thereto can he exert a sufficient pres- 
sure to overcome his own weight against as imponderable 
a fluid as air. If air were as heavy as water, instead of 
700 times lighter, it would be as easy to fly as to swim. 
The bird can fly because of the great surface, powerful 
construction, and rapid movement of its wings, in propor- 
tion to the weight of its body. But compared with the 
rest of the animal kingdom, flying birds are all of small size. 
Helmholz considered that the vulture represented the 
heaviest body that could possibly be raised and kept aloft 
by the exercise of muscular power, and it is understood 
that vultures have considerable difficulty in ascending; 
so much so that unless in a position to take a short pre- 
liminary run they are easily captured. 

Every one has noticed a second type of bird flight — 
soaring. It is this flight which is exactly imitated in a 
glider. An aeroplane differs from a soaring bird only in 
that it carries with it a producer of forward impetus — the 



The Delights and Dangers of Flying 



13 



propeller — so that the soaring flight may last indefinitely: 
whereas a soaring bird gradually loses speed and descends. 




In a Meteoric Shower 

A third and rare type of bird flight has been called sailing. 
The bird faces the wind, and with wings outspread and 
their forward edge elevated rises while being forced back- 
ward under the action of the breeze. As soon as the wind 



14 Flying Machines Today 

somewhat subsides, the bird turns and soars in the desired 
direction. Flight is thus accomplished without muscular 
effort other than that necessary to properly incline the wings 
and to make the turns. It is practicable only in squally 
winds, and the birds which practice " sailing" — the 
albatross and frigate bird — are those which live in the 
lower and more disturbed regions of the atmosphere. This 
form of flight has been approximately imitated in the 
manceuvering of aeroplanes. 

Comparison of flying machines and ships suggests many 
points of difference. Water is a fluid of great density, with 
a definite upper surface, on which marine structures 
naturally rest. A vessel in the air may be at any elevation 
in the surrounding rarefied fluid, and great attention is 
necessary to keep it at the elevation desired. The air 
has no surface. The air ship is like a submarine — the 
dirigible balloon of the sea — and perhaps rather more 
safe. An ordinary ship is only partially immersed; the 
resistance of the fluid medium is exerted over a portion 
only of its head end: but the submarine or the flying 
machine is wholly exposed to this resistance. The sub- 
marine is subjected to ocean currents of a very few miles 
per hour, at most; the currents to which the flying machine 
may be exposed exceed a mile a minute. Put a submarine 
in the Whirlpool Rapids at Niagara and you will have 
possible air ship conditions. 

A marine vessel may tack, i.e., may sail partially against 
the wind that propels it, by skilful utilization of the resist- 



The Delights and Dangers of Flying 



15 




How a Boat Tacks 
The wind always exerts a pressure, per- 
pendicular to the sail, svhich tends to 
drift the boat sidewise (R) and also to propel 
it forward ( L ) . Sidewise movement 
is resisted by the hull. 
An air ship cannot tack 
because there is no such s \Q 

resistance to drift. 



Go about 
at this point 



1 6 Flying Machines Today 

ance to sidewise movement of the ship through the water: 
but the flying machine is wholly immersed in a single 
fluid, and a head wind is nothing else than a head wind, 
producing an absolute subtraction from the proper speed 
of the vessel. 

Aerial navigation is thus a new art, particularly when 
heavier- than-air machines are used. We have no heavier- 
than-water ships. The flying machine must work out its 
own salvation. 



SOARING FLIGHT BY MAN 

Flying machines have been classified as follows: — 

Lighter than Air 
Fixed balloon. 
Drifting balloon, 
Sailing balloon, 
Dirigible balloon 

rigid (Zeppelin), 

ballonetted. 

Heavier than Air 
Orthopter, 
Helicopter, 
Aeroplane 

monoplane, 
multiplane. 

We will fall in with the present current of popular interest 
and consider the aeroplane — that mechanical grasshop- 
per — first. 

What Holds It Up? 

When a flat surface like the side of a house is exposed to 
the breeze, the velocity of the wind exerts a force or pres- 
sure directly against the surface. This principle is taken 
into account in the design of buildings, bridges, and other 

17 



i8 



Flying Machines Today 




Octave Chanute (died 19 10) 
To the researches of Chanute and Langley must be 
ascribed much cf American progress in aviation. 



Soaring Flight by Man 



19 



structures. The pressure exerted per square foot of sur- 
face is equal (approximately) to the square of the wind 
velocity in miles per hour, divided by 300. Thus, if the 
wind velocity is thirty miles, the pressure against a house 
wall on winch it acts directly is 30 X 30 -r- 300 = 3 pounds 
per square foot: if the wind velocity is sixty miles, the 
pressure is 60 X 60 -f- 300 = 12 pounds: if the velocity is 
ninety miles, the pressure is 90 X 90 -f- 300 = 27 pounds, 
and so on. 




If the wind blows obliquely toward the surface, instead 
of directly, the pressure at any given velocity is reduced, 
but may still be considerable. Thus, in the sketch, let ab 
represent a wall, toward which we are looking downward, 
and let the arrow V represent the direction of the wind. 
The air particles will follow some such paths as those 
indicated, being deflected so as to finally escape around 
the ends of the wall. The result is that a pressure is pro- 
duced which may be considered to act along the dotted 



20 



Flying Machines Today 



line P, perpendicular to the wall. This is the invariable 
law: that no matter how oblique the surface may be, with 
reference to the direction of the wind, there is always a 
pressure produced against the surface by the wind, and 
this pressure always acts in a direction perpendicular to the 
surface. The amount of pressure will depend upon the 
wind velocity and the obliquity or inclination of the surface 
(ab) with the wind (V). 

Now let us consider a kite — the " immediate ancestor" 
of the aeroplane. The surface ab is that of the kite itself, 




held by its string cd. We are standing at one side and 
looking at the edge of the kite. The wind is moving 
horizontally against the face of the kite, and produces a 
pressure P directly against the latter. The pressure tends 
both to move it toward the left and to lift it. If the tend- 
ency to move toward the left be overcome by the string, 
then the tendency toward lifting may be offset — and in 
practice is offset — by the weight of the kite and tail. 

We may represent the two tendencies to movement 
produced by the force P, by drawing additional dotted 
lines, one horizontally to the left (R) and the other verti- 



Soaring Flight by Man 21 

cally (L) ; and it is known that if we let the length of the 
line P represent to some convenient scale the amount of 
direct pressure, then the lengths of R and L will also 
represent to the same scale the amounts of horizontal and 
vertical force due to the pressure. If the weight of kite and 
tail exceeds the vertical force L, the kite will descend: if 
these weights are less than that force, the kite will ascend. 
If they are precisely equal to it, the kite will neither ascend 
nor descend. The ratio of L to R is determined by the 
slope of P; and this is fixed by the slope of ab; so that we 
have the most important conclusion: not only does the 
amount of direct pressure (P) depend upon the obliquity of 
the surface with the breeze (as has already been shown), but 
the relation of vertical force (which sustains the kite) to hori- 
zontal force also depends on the same obliquity. For example, 
if the kite were flying almost directly above the boy who 
held the string, so that ab became almost horizontal, P 
would be nearly vertical and L would be much greater 
than R. On the other hand, if ab were nearly vertical, the 
kite flying at low elevation, the string and the direct pres- 
sure would be nearly horizontal and L would be much less 
than R. The force L which lifts the kite seems to increase 
while R decreases, as the kite ascends: but L may not 
actually increase, because it depends upon the ?.mount of 
direct pressure, P. as well as upon the direction of this 
pressure; and the amount of direct pressure steadily 
decreases during ascent, on account of the increasing 
obliquity of ab with V. All of this is of course dependent 



22 Flying Machines Today 

on the assumption that the kite always has the same 
inclination to the string, and the described resolution of 
the forces, although answering for illustrative purposes, 
is technically incorrect. 

It seems to be the wind velocity, then, which holds up the 
kite: but in reality the string is just as necessary as the 
wind. If there is no string, and the wind blows the kite 
with it, the kite comes down, because the pressure is wholly 
due to a relative velocity as between kite and wind. The 
wind exerts a pressure against the rear of a railway train, 
if it happens to be blowing in that direction, and if we 
stood on the rear platform of a stationary train we should 
feel that pressure : but if the train is started up and caused 
to move at the same speed as the wind there would be no 
pressure whatever. 

One of the very first heayier-than-air flights ever recorded 
is said to have been made by a Japanese who dropped 
bombs from an immense man-carrying kite during the 
Satsuma rebellion of 1869. The kite as a flying machine 
has, however, two drawbacks: it needs the wind — it can- 
not fly in a calm — and it stands still. One early effort 
to improve on this situation was made in 1856, when a 
man was towed in a sort of kite which was hauled by a 
vehicle moving on the ground. In February of the present 
year, Lieut. John Rodgers, U.S.N., was lifted 400 feet 
from the deck of the cruiser Pennsylvania by a train of 
eleven large kites, the vessel steaming at twelve knots 
against an eight-knot breeze. The aviator made obser- 



Soaring Flight by Man 23 

rations and took photographs for about fifteen minutes, 
while suspended from a tail cable about 100 feet astern. 
In the absence of a sufficient natural breeze, an artificial 
wind was thus produced by the motion imparted to the 
kite; and the device permitted of reaching some destina- 
tion. The next step was obviously to get rid of the tractive 
vehicle and tow rope by carrying propelling machinery 
on the kite. This had been accomplished by Langley in 
1896, who flew a thirty-pound model nearly a mile, using a 
steam engine for power. The gasoline engine, first em- 
ployed by Santos-Dumont (in a dirigible balloon) in 1901, 
has made possible the present day aeroplane. 




What "keeps it up." in the case of this device, is likewise 
its velocity. Looking from the side, ab is the sail of the 
aeroplane, which is moving toward the right at such speed 
as to produce the equivalent of an air velocity V to the 
left. This velocity causes the direct pressure P, equivalent 
to a lifting force L and a retarding force R. The latter is 
the force which must be overcome by the motor: the 



24 



Flying Machines Today 



former must suffice to overcome the whole weight of the 
apparatus. Travel in an aeroplane is like skating rapidly 
over very thin ice: the air literally " doesn't have time to 
get away from underneath." 

If we designate the angle made by the wings (ab) with 
the horizontal (T) as B, then P increases as B increases, 



10 

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Angles in Degrees 

Direct, Lifting, and Resisting Forces 
If the pressure is 10 lbs. when the wind blows directly toward the 
surface (at an angle of 90 degrees), then the forces for other angles of 
direction are as shown on the diagram. The amounts of all forces de- 
pend upon the wind velocity: that assumed in drawing the diagram 
was about 55 miles per hour. But the relations of the forces are the 
same for the various angles, no matter what the velocity. 

while (as has been stated) the ratio of L to R decreases. 
When the angle B is a right angle, the wings being in the 
position a'b', P has its maximum value for direct wind- 
's or of the square of the velocity, in pounds per square foot; 
but L is zero and R is equal to P. The plane would have no 



Soaring Flight by Man 25 

lifting power. When the angle B becomes zero, position 
a "b" , wings being horizontal, P becomes zero and (so far 
as we can now judge) the plane has neither lifting power 
nor retarding force. At some intermediate position, like 
ab, there will be appreciable lifting and retarding forces. 
The chart shows the approximate lifting force, in pounds 
per square foot, for various angles. This force becomes a 
maximum at an angle of 45 ° (half a right angle). We are 
not yet prepared to consider why in all actual aeroplanes 
the angle of inclination is much less than this. The reason 
will be shown presently. At this stage of the discussion 
we may note that the lifting power per square foot of sail 
area varies with 

the square of the velocity, and 

the angle of inclination. 
The total lifting power of the whole plane will also vary 
with its area. As we do not wish this whole lifting power 
to be consumed in overcoming the dead weight of the ma- 
chine itself, we must keep the parts light, and in particular 
must use for the wings a fabric of light weight per unit of 
surface. These fabrics are frequently the same as those 
used for the envelopes of balloons. 

Since the total supporting power varies both with the 
sail area and with the velocity, we may attain a given 
capacity either by employing large sails or by using high 
speed. The size of sails for a given machine varies in- 
versely as the square of the speed. The original Wright 
machine had 500 square feet of wings and a speed of forty 



26 



Flying Machines Today 



miles per hour. At eighty miles per hour the necessary sail 
area for this machine would be only 125 square feet; and 
at 160 miles per hour it would be only 31^ square feet: 
while if we attempted to run the machine at ten miles per 
hour we should need a sail area of 8000 square feet. This 
explains why the aeroplane cannot go slowly. 

It would seem as if when two or more superposed sails 
were used, as in biplanes, the full effect of the air would 
not be realized, one sail becalming the other. Experiments 
have shown this to be the case; but there is no great reduc- 
tion in lifting power unless the distance apart is consider- 
ably less than the width of the planes. 

In all present aeroplanes the sails are concaved on the 
under side. This serves to keep the air from escaping 
from underneath as rapidly as it otherwise would, and 
increases the lifting power from one-fourth to one-half over 
that given by our -$$-$ rule: the divisor becoming roughly 
about 230 instead of 300. 








Why are the wings placed crosswise of the machine, 
when the other arrangement — the greatest dimension 
in the line of flight — would seem to be stronger? This 



Soaring Flight by Man 27 

is also done in order to ''keep the air from escaping from 
underneath. 1 ' The sketch shows how much less easily 
the air will get away from below a wing of the bird-like 
spread-out form than from one relatively long and narrow 
but of the same area. 

A sustaining force of two pounds per square foot of area 
has been common in ordinary aeroplanes and is perhaps 
comparable with the results of bird studies: but this figure 
is steadily increasing as velocities increase. 

Why so Many Sails? 

Thus far a single wing or pair of wings would seem to 
fully answer for practicable flight: yet every actual aero- 
plane has several small wings at various points. The 
necessity for one of these had already been discovered in the 
kite, which is built with a balancing tail. In the sketch 
on page 18 it appears that the particles of air which are 
near the upper edge of the surface are more obstructed 
in their effort to get around and past than those near the 
lower edge. They have to turn almost completely about, 
while the others are merely deflected. This means that on 
the whole the upper air particles will exert more pressure 
than the lower particles and that the " center of pressure" 
(the point where the entire force of the wind may be 
assumed to act) will be, not at the center of the surface, but 
at a point some distance above this center. This action is 
described as the " displacement of the center of pressure." 
It is known that the displacement is greatest for least 



28 Flying Machines Today 

inclinations of surface (as might be surmised from the 
sketch already referred to), and that it is always propor- 
tional to the dimension of the surface in the direction of 
movement; i.e., to the length of the line ab. 

If the weight W of the aeroplane acts downward at the 
center of the wing (at o in the accompanying sketch), 
while the direct pressure P acts at some point c farther 
along toward the upper edge of the wing, the two forces W 
and P tend to revolve the whole wing in the direction 
indicated by the curved arrow. This rotation, in an aero- 




plane, is resisted by the use of a tail plane or planes, such 
as mn. The velocity produces a direct pressure P' on the 
tail plane, which opposes, like a lever, any rotation due to 
the action of P. It may be considered a matter of rather 
nice calculation to get the area and location of the tail 
plane just right: but we must remember that the amount 
of pressure P f can be greatly varied by changing the incli- 
nation of the surface nm. This change of inclination is 
effected by the operator, who has access to wires which are 
attached to the pivoted tail plane. It is of course permis- 
sible to place the tail plane in front of the main planes — 



Soaring Flight by Man 29 

as in the original Wright machine illustrated: but in this 
case, with the relative positions of W and P already shown, 
the forward edge of the tail plane would have to be de- 
pressed instead of elevated. The illustration shows the 
tail built as a biplane, just as are the principal wings 
(page 141). 

Suppose the machine to be started with the tail plane in a 
horizontal position. As its speed increases, it rises and at 
the same time (if the weight is suspended from the center 
of the main planes) tilts backward. The tilting can be 
stopped by swinging the tail plane on its pivot so as to 
oppose the rotative tendency. If this control is not carried 
too far, the main planes will be allowed to maintain some 
of their excessive inclination and ascent will continue. 
When the desired altitude has been attained, the inclina- 
tion of the main planes will, by further swinging of the tail 
plane, be reduced to the normal amount, at which the 
supporting power is precisely equal to the load; and the 
machine will be in vertical equilibrium: an equilibrium 
which demands at every moment, however, the attention 
of the operator. 

In many machines, ascent and tilting are separately 
controlled by using two sets of transverse planes, one set 
placed forward, and the other set aft, of the main planes. 
In any case, quick ascent can be produced only by an 
increase in the lifting force L (see sketch, page 24) of the 
main planes: and this force is increased by enlarging the 
angle of inclination of the main planes, that is, by a con- 



3° 



Flying Machines Today 



trolled and partial tilting. The forward transverse wing 
which produces this tilting is therefore called the elevating 
rudder or elevating plane. The rear transverse plane 
which checks the tilting and steadies the machine is often 




Roe's Triplane at Wembley 
(From Brewer's Art of Aviation) 

described as the stabilizing plane. Descent is of course 
produced by decreasing the angle of inclination of the main 
planes. 

Steering 

If we need extra sails for stability and ascent or descent, 
we need them also for changes of horizontal direction. 
Let ab be the top view of the main plane of a machine, 
following the course xy. At rs is a vertical plane called the 
steering rudder. This is pivoted, and controlled by the 



Soaring Flight by Man 



3i 



operator by means of the wires /, u. Let the rudder be 
suddenly shifted to the position rV. It will then be sub- 



1— 

\ 


3'— - 


t 






y 


\ 




II 


/-^ia< 


- — 






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jected to a pressure P' which will swing the whole machine 
into the new position shown by the dotted lines, its course 
becoming x'y' . The steering rudder may of course be 
double, forming a vertical biplane, as in the Wright ma- 
chine shown below. 

Successful steering necessitates lateral resistance to 
drift, i.e., a fulcrum. This is provided, to some extent, by 



Steering Rudder (double) 



Elevating 
/"Plane 




Two Vertical 
Fulcrum Planes 



Recent Type of Wright Biplane 



the stays and frame of the machine; and in a much more 
ample way by the vertical planes of the original Voisin 
cellular biplane. A recent Wright machine had vertical 
planes forward probably intended for this purpose. 



32 Flying Machines Today 

It now begins to appear that the aviator has a great 
many things to look after. There are many more things 
requiring his attention than have yet been suggested. No 
one has any business to attempt flying unless he is super- 
latively cool-headed and has the happy faculty of instinc- 
tively doing the right thing in an emergency. Give a 
chauffeur a high power automobile running at maximum 
speed on a rough and unfamiliar road, and you have some 
conception of the position of the operator of an aeroplane. 
It is perhaps not too much to say that to make the two 
positions fairly comparable we should blindfold the chauf- 
feur. 

Broadly speaking, designers may be classed in one of 
two groups — those who, like the Wrights, believe in 
training the aviator so as to qualify him to properly handle 
his complicated machine; and those who aim to simplify 
the whole question of control so that to acquire the neces- 
sary ability will not be impossible for the average man. 
If aviation is to become a popular sport, the latter ideal 
must prevail. The machines must be more automatic 
and the aviator must have time to enjoy the scenery. In 
France, where amateur aviation is of some importance, 
progress has already been made in this direction. The uni- 
versal steering head, for example, which not only revolves 
like that of an automobile, but is hinged to permit of 
additional movements, provides for simultaneous control 
of the steering rudder and the main plane warping, while 
scarcely demanding the conscious thought of the operator. 



TURNING CORNERS 

A year elapsed after the first successful flight at Kitty 
Hawk before the aviator became able to describe a circle 
in the air. A later date, 1907, is recorded for the first 
European half-circular flight: and the first complete 
circuit, on the other side of the water, was made a year 
after that; by both biplane and monoplane. It was in 
the same year that Louis Bleriot made the pioneer cross- 
country trip of twenty-one miles, stopping at will en route 
and returning to his starting point. 



What Happens When Making a Turn 

We are looking downward on an aeroplane ab which 
has been moving along the straight path cd. At d it begins 




to describe the circle de, the radius of which is od, around 

33 



34 Flying Machines Today 

the center o. The outer portion of the plane, at the edge 
b, must then move faster than the inner edge a. We have 
seen that the direct air pressure on the plane is propor- 
tional to the square of the velocity. The direct pressure 
P (see sketch on page 22) will then be greater at the outer 
than at the inner limb ; the lifting force L will also be greater 
and the outer limb will tend to rise, so that the plane 
(viewed from the rear) will take the inclined position shown 
in the lower view : and this inclination will increase as long 
as the outer limb travels faster than the inner limb; that 
is, as long as the orbit continues to be curved. Very soon, 
then, the plane will be completely tipped over. 

Necessarily, the two velocities have the ratio om : om f ; 
the respective lifting forces must then be proportional to 
the squares of these distances. The difference of lifting 
forces, and the tendency to overturn, will be more im- 
portant as the distances most greatly differ: which is the 
case when the distance om is small as compared with mm' . 
The shorter the radius of curvature, the more dangerous, 
for a given machine, is a circling flight: and in rounding a 
curve of given radius the most danger is attached to the 
machine of greatest spread of wing. 

Lateral Stability 

This particular difficulty has considerably delayed the 
development of the aeroplane. It may, however, be over- 
come by very simple methods — simple, at least as far as 
their mechanical features are concerned. If the outer 






Turning Corners 



35 



limb of the plane is tilted upward, it is because the wind 
pressure is greater there. The wind pressure is greater 
because the velocity is greater. We have only to increase 
the wind pressure at the inner limb, in order to restore 
equilibrium. This cannot be done by adjusting the velocity, 
because the velocity is fixed by the curvature of path re- 
quired: but the total wind pressure depends upon the sail 
area as well as the velocity; so that by increasing the sur- 
face at the inner limb we may equalize the value of L, the 
lifting force, at the two ends of the plane. This increase 
of surface must be a temporary affair, to be discontinued 
when moving along a straight course. 




Side View 



Rear View 



r 



The Aileron 



Let us stand in the rear of an aeroplane, the main wing 
of which is represented by ab. Let the small fan-shaped 
wings c and d be attached near the ends, and let the control 
wires, e,f, passing to the operator at g, be employed to close 
and unclasp the fans. If these fans are given a forward 
inclination at the top, as indicated in the end view, they 
will when spread out exert an extra lifting force. A fan 



36 Flying Machines Today 

will be placed at each end. They will be ordinarily folded 
up: but when rounding a curve the aviator will open the 
fan on the inner or more slowly moving limb of the main 
plane. This represents one of the first forms of the aileron 
or wing- tip for lateral control. 

The more common present form of aileron is that shown 
in the lower sketch, at J and t. The method of control is 
the same. 

The cellular Voisin biplanes illustrate an attempt at 
self-sufficing control, without the interposition of the avia- 
tor. Between the upper and lower sails of the machine 
there were fore and aft vertical partitions. The idea was 
that when the machine started to revolve, the velocity of 
rotation would produce a pressure against these partitions 




Front View °4 ^ / 



/ 



Wing Tipping 



which would obstruct the tipping. But rotation may take 
place slowly, so as to produce an insufficient pressure for 
control, and yet be amply sufficient to wreck the apparatus. 
The use of extra vertical rudder planes, hinged on a hori- 
zontal longitudinal axis, is open to the same objection. 

Wing Warping 

In some monoplanes with the inverted V wing arrange- 
ment, a dipping of one wing answers, so to speak, to increase 



Turning Corners 37 

its concavity and thus to augment the lifting force on that 
side. The sketch shows the normal and distorted arrange- 
ment of wings : the inner limb being the one bent down in 
rounding a curve. An equivalent plan was to change the 
angle of inclination of one-half the sail by swinging it 
about a horizontal pivot at the center or at the rear 
edge: some machines have been built with sails divided 
in the center. The obvious objection to both of these 
plans is that too much mechanism is necessary in order 
to distort what amounts to nearly half the whole ma- 
chine. They remind one of Charles Lamb's story of the 
discovery of roast pig. 
The distinctive feature of the Wright machines lies in 




a 1 



Wing Warping 



the warping or distorting of the ends only of the main 
planes. This is made possible, not by hinging the wings in 
halves, but by the flexibility of the framework, winch is 
sufficiently pliable to permit of a considerable bending 
without danger. The operator, by pulling on a stout wire 
linkage, may tip up (or down) the corners cc r of the sails 
at one limb, thus decreasing or increasing the effective 
surface acted on by the wind, as the case may require. 



38 Flying Machines Today 

The only objection is that the scheme provides one more 
thing for the aviator to think about and manipulate. 

Automatic Control 

Let us consider again the condition of things when 
rounding a curve, as in the sketch on page 32. As long 
as the machine is moving forward in a straight line, the 
operator sits upright. When it begins to tip, he will un- 
consciously tip himself the other way, as represented by 
the line xy in the rear view. Any bicyclist will recognize 
this as plausible. Why not take advantage of this involun- 
tary movement to provide a stabilizing force? If operat- 
ing wires are attached to the aviator's belt and from thence 
connected with ailerons or wing-warping devices, then by 
a proper proportioning of levers and surfaces to the prob- 
able swaying of the man, the control may become automatic. 
The idea is not new; it has even been made the subject of 
a patent. 

The Gyroscope 

This device for automatic control is being steadily 
developed and may ultimately supersede all others. It 
uses the inertia of a fast-moving fly wheel for control, in a 
manner not unlike that contemplated in proposed methods 
of automatic balancing by the action of a suspended pendu- 
lum. Every one has seen the toy gyroscope and perhaps 
has wondered at its mysterious ways. The mathematical 
analysis of its action fills volumes : but some idea of what 
it does, and why, may perhaps be gathered at the expense 



Turning Corners 



39 



of a very small amount of careful attention. The wheel 
acbd, a thin disc, is spinning rapidly about the axle 0. In 
the side view, ab shows the edge of the wheel, and oo' the 






a 
End 


The Gyroscope 


a 
Side 



axle. This axle is not fixed, but may be conceived as held 
in some one's fingers. Now suppose the right-hand end 
of the axle (0') to be suddenly moved toward us (away 
from the paper) and the left-hand (0) to be moved away. 



4o Flying Machines Today 

The wheel will now appear in both views as an ellipse, and 
it has been so represented, as afbe. Now, any particle, like 
x, on the rim of the wheel, will have been regularly moving 
in the circular orbit cb. The tendency of any body in 
motion is to move indefinitely in a straight line. The 
cohesion of the metal of the disc prevents the particle x 
from flying off at a straight line tangent, xy, and it is con- 
strained, therefore, to move in a circular orbit. Unless 
some additional constraint is imposed, it will at least 
remain in this orbit and will try to remain in its plane of 
rotation. When the disc is tipped, the plane of rotation 
is changed, and the particle is required, instead of (so to 
speak) remaining in the plane of the paper — in the side 
view — to approach and pass through that plane at b and 
afterward to continue receding from us. Under ordinary 
circumstances, this is just what it would do: but if, as in 
the gyroscope, the axle oo' is perfectly free to move in any 
direction, the particle x will refuse to change its direction 
of rotation. Its position has been shifted: it no longer 
lies in the plane of the paper: but it will at least persist 
in rotating in a parallel plane: and this persistence forces 
the revolving disc to swing into the new position indi- 
cated by the curve kg, the axis being tipped into the 
position pq. The whole effect of all particles like x 
in the entire wheel will be found to produce precisely 
this condition of things: if we undertake to change the 
plane of rotation by shifting the axle in a horizontal 
plane, the device itself will (if not prevented) make a 



Turning Corners 41 

further change in the plane of rotation by shifting the 
axle in a vertical plane. 

A revolving disc mounted on the gyroscopic framework 
therefore resists influences tending to change its plane of 
rotation. If the device is placed on a steamship, so that 
when the vessel rolls a change of rotative plane is produced, 
the action of the gyroscope will resist the rolling tendency 
of the vessel. All that is necessary is to have the wheel 
revolving in a fore and aft plane on the center line of the 
vessel, the axle being transverse and firmly attached to 
the vessel itself. A small amount of power (consumed in 
revolving the wheel) gives a marked steadying effect. The 
same location and arrangement on an aeroplane will suffice 
to overcome tendencies to transverse rotation when round- 
ing curves. The device itself is automatic, and requires 
no attention, but it does unfortunately require power to 
drive it and it adds some weight. 

The gyroscope is being tested at the present time on 
some of the aeroplanes at the temporary army camps 
near San Antonio, Texas. 

Wind Gusts 

This feature of aeronautics is particularly important, 
because any device which will give automatic stability 
when turning corners will go far toward making aviation 
a safe amusement. Inequalities of velocity exist not only 
on curves, but also when the wind is blowing at anything 
but uniform velocity across the whole front of the machine. 



42 Flying Machines Today 

The slightest "flaw" in the wind means an at least tempo- 
rary variation in lifting force of the two arms. Here is a 
pregnant source of danger, and one which cannot be left 
for the aviator to meet by conscious thought and action. 
It is this, then, that blindfolds him: he cannot see the 
wind conditions in advance. The conditions are upon 
him, and may have done their destructive work, before 
he can prepare to control them. We must now study 
what these conditions are and what their influence may 
be on various forms of aerial navigation: after which, 
a return to our present subject will be possible. 



AIR AND THE WIND 

The air that surrounds us weighs about one-thirteenth 
of a pound per cubic foot and exerts a pressure, at sea 
level, of nearly fifteen pounds per square inch. Its tem- 
perature varies from 30 below to ioo° above the Fahren- 
heit zero. The pressure of the air decreases about one- 
half pound for each thousand feet of altitude; at the top 
of Mt. Blanc it would be, therefore, only about six pounds 
per square inch. The temperature also decreases with the 
altitude. The weight of a cubic foot, or density, which, 
as has been stated, is one-thirteenth of a pound ordinarily ? 
varies with the pressure and with the temperature. The 
variation with pressure may be described by saying that 
the quotient of the pressure by the density is constant: 
one varies in the same ratio as the other. Thus, at the 
top of Mt. Blanc (if the temperature were the same as at 
sea level) , the density of air would be about ■£$ X tV = £5 : 
less than half what it is at sea level. As to temperature, 
if we call our Fahrenheit zero 460°, and correspondingly 
describe other temperatures — for instance, say that water 
boils at 672° — then (pressure being unchanged) the prod- 
uct of the density and the temperature is constant. If the 
density at sea level and zero temperature is one-thirteenth 
pound, then that at sea level and 460 Fahrenheit would be 

43 



44 Flying Machines Today 

A 13 ~~ 26* 



o + 460 v , 



460 + 460 

These relations are particularly important in the design 
of all balloons, and in computations relating to aeroplane 
flight at high altitudes. We shall be prepared to appreciate 
some of their applications presently. 

Generally speaking, the atmosphere is always in motion, 
and moving air is called wind. Our meteorologists first 
studied winds near the surface of the ground: it is only 
of late years that high altitude measurements have been 
considered practically desirable. Now, records are ob- 
tained by the aid of kites up to a height of nearly four 
miles: estimates of cloud movements have given data 
on wind velocities at heights above six miles: and much 
greater heights have been obtained by free balloons equipped 
with instruments for recording temperatures, pressures, 
altitude, time, and other data. 

When the Eiffel Tower was completed, it was found that 
the average wind velocity at its summit was about four 
times that at the base. Since that time, much attention 
has been given to the contrasting conditions of surface and 
upper breezes as to direction and velocity. 

Air is easily impeded in its movement, and the well- 
known uncertainties of the weather are closely related to 
local variations in atmospheric pressure and temperature. 
When near the surface of the ground, impingement against 
irregularities therein — hills, cliffs, and buildings — makes 
the atmospheric currents turbulent and irregular. Where 



Air and the Wind 



45 



there are no surface irregularities, as on a smooth plain 
or over water, the friction of the air particles passing over 
the surface still results in a stratification of velocities. 
Even on a mountain top, the direction and speed of the 
wind are less steady than in the open where measured by 
a captive balloon. The stronger the wind, the greater, 
relatively, is the irregularity produced by surface condi- 
tions. Further, the earth's surface and its features form a 




Diurnal Temperatures at Different Heights 
(From Rotch's The Conquest of the Air) 

vast sponge for sun heat, which they transfer in turn to the 
air in an irregular way, producing those convectional cur- 
rents peculiar to low altitudes, the upper limit of which is 
marked by the elevation of the cumulus clouds. Near the 
surface, therefore, wind velocities are lowest in the early 
morning, rising to a maximum in the afternoon. 

Every locality has its so-called " prevailing winds." 
Considering the compass as having eight points, one of 



46 Flying Machines Today 

those points may describe as many as 40% of all the winds 
at a given place. The direction of prevalence varies with 
the season. The range of wind velocities is also a matter of 
local peculiarity. In Paris, the wind speed exceeds thirty- 
four miles per hour on only sixty-eight days in the average 
year, and exceeds fifty-four miles on only fifteen days. 
Observations at Boston show that the velocity of the wind 
exceeds twenty miles per hour on half the days in winter 
and on only one-sixth the days in summer. Our largest 
present dirigible balloons have independent speeds of 
about thirty-four miles per hour and are therefore available 
(at some degree of effectiveness) for nearly ten months of 
the year, in the vicinity of Paris. In a region of low wind 
velocities — like western Washington, in this country — 
they would be available a much greater proportion of the 
time. To make the dirigible able to at least move nearly 
every day in the average year — in Paris — it must be 
given a speed of about fifty-five miles per hour. 

Figures as to wind velocity mean little to one unaccus- 
tomed to using them. A five-mile breeze is just " pleas- 
ant." Twelve miles means a brisk gale. Thirty miles 
is a high wind: fifty miles a serious storm (these are the 
winds the aviator constantly meets): one hundred miles 
is perhaps about the maximum hurricane velocity. 

As we ascend from the surface of the earth, the wind 
velocity steadily increases; and the excess velocity of 
winter winds over summer winds is as steadily augmented. 
Thus, Professor Rotch found the following variations : 



Air and the Wind 



47 



Altitude in Feet 

656 
1.800 
3,280 

8,190 

1 1, .440 
17,680 
20,970 
31,100 

Altitude in Feet 

656 to 3,280 

3.280 to 9.810 

9,810 to 16,400 

16.400 to 22,950 

22,950 to 29.500 



Annual Average 
Wind Velocity, Feet per Second 

23-15 
32.10 

35- 
41. 
50.8 
81.7 



Average Wind Velocities. Feet per Second 
Summer Winter 



24-55 
26.85 

34-65 
62.60 
77.00 



28.80 
48.17 
71.00 
161. 5 



These results are shown in a more striking w r ay by the 

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5000 



10000 15000 20000 
Altitude in Feet 



25000 30000 



chart. At a five or six mile height, double-barreled hur- 
ricanes at speeds exceeding 200 miles per hour are not 



48 Flying Machines Today 

merely possible; they are part of the regular order of 
things, during the winter months. 

The winds of the upper air, though vastly more power- 
ful, are far less irregular than those near the surface: and 
the directions of prevailing winds are changed. If 50% 
of the winds, at a given location on the surface, are from 
the southwest, then at as moderate an elevation as even 
1000 feet, the prevailing direction will cease to be from 
southwest; it may become from west-southwest; and the 
proportion of total winds coming from this direction will 
not be 50%. These factors are represented in meteorologi- 
cal papers by what is known as the wind rose. From the 
samples shown, we may note that 40% of the surface 
winds at Mount Weather are from the northwest; while 
at some elevation not stated the most prevalent of the 
winds (22% of the total) are westerly. The direction of 
prevalence has changed through one-eighth of the possible 
circle, and in a counter-clockwise direction. This is con- 
trary to the usual variation described by the so-called 
Broun's Law, which asserts that as we ascend the direc- 
tion of prevalence rotates around the circle like the hands 
of a watch; being, say, from northwest at the surface, 
from north at some elevation, from northeast at a still 
higher elevation, and so on. At a great height, the change 
in direction may become total: that is, the high altitude 
winds blow in the exactly opposite direction to that of the 
surface winds. In the temperate regions, most of the 
high altitude winds are from the west: in the tropics, 




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50 Flying Machines Today 

the surface winds blow toward the west and toward the 
equator; being northeasterly in the northern hemisphere 
and southeasterly in the southern: and there are un- 
doubtedly equally prevalent high-altitude counter- trades. 
The best flying height for an aeroplane over a flat field 
out in the country is perhaps quite low — 200 or 300 feet: 
but for cross-country trips, where hills, rivers, and buildings 
disturb the air currents, a much higher elevation is neces- 
sary; perhaps 2000 or 3000 feet, but in no case more than 
a mile. The same altitude is suitable for dirigible balloons. 
At these elevations we have the conditions of reasonable 
warmth, dryness, and moderate wind velocities. 

Sailing Balloons 

In classifying air craft, the sailing balloon was mentioned 
as a type intermediate between the drifting balloon and 
the dirigible. No such type has before been recognized: 
but it may prove to have its field, just as the sailing vessel 
on the sea has bridged the gap between the raft and the 
steamship. It is true that tacking is impossible, so that 
our sailing balloons must always run before the wind: but 
they possess this great advantage over marine sailing craft, 
that by varying their altitude they may always be able to 
find a favorable wind. This implies adequate altitude 
control, which is one of the problems not yet solved for 
lighter- than-air flying machines: but when it has been 
solved we shall go far toward attaining a dirigible balloon 
without motor or propeller; a true sailing craft. 



Air and the Wind 



5i 



This means more study and careful utilization of strati- 
fied atmospheric currents. Professor Rotch suggests the 
utilization of the upper westerly wind drift across the 
American continent and the Atlantic Ocean, which would 
carry a balloon from San Francisco to southern Europe at 



SAFETY VALVE CORD 



COLLAR 
SUSPENDING CORDS. 



STIFFENER 

SAFETY VALVE 



RIPPING STRIP 




P STRIP CCRD 



FINAL STITCHES 



FIRST KNOTS 
SECOND KNOTS 
THIRD KNOTS 



OPENING FOR CORD 



■ANCHOR 

Diagram of Parts of a Drifting Balloon 



a speed of about fifty feet per second — thirty-four miles 
per hour. Then by transporting the balloon to northern 
Africa, the northeast surface trade wind would drive it 
back to the West Indies at twenty-five miles .per hour. 
This without any motive power: and since present day 
dirigibles are all short of motive power for complete 



52 



Flying Machines Today 



dirigibility, we must either make them much more power- 
ful or else adopt the sailing principle, which will permit of 




Glidden and Stevens Getting Away in the " Boston " 
(Leo Stevens, N.Y.) 

actually decreasing present sizes of motors, or even possibly 
of omitting them altogether. Our next study is, then, 
logically, one of altitude control in balloons. 



Air and the Wind 53 

Field and Speed 

An aerostat (non-dirigible balloon), unless anchored, 
drifts at the speed of the wind. To the occupants, it seems 
to stand still, while the surface of the earth below appears 
to move in a direction opposite to that of the wind. In 
the sketch, if the independent velocity of a dirigible balloon 



be PB, the wind velocity PV, then the actual course pur- 
sued is PR, although the balloon always points in the 
direction PB, as shown at 1 and 2. If the speed of the wind 
exceed that of the balloon, there will be some directions 
in which the latter cannot progress. Thus, let PV be the 



x ^ 




wind velocity and TV the independent speed of the balloon. 
The tangents PX, PX' , include the whole " field of action" 
possible. The wind direction may change during flight, 



54 



Flying Machines Today 



so that the initial objective point may become unattain- 
able, or an initially unattainable point may be brought 
within the field. The present need is to increase inde- 
pendent speeds from thirty or forty to fifty or sixty miles 
per hour, so that the balloon will be truly dirigible (even if 
at low effectiveness) during practically the whole year. 





N / , *£ 




; 


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L Miles. V c 


Albany < 


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New York/ 


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s.s.w. 



Suppose a dirigible to start on a trip from New York 
to Albany, 150 miles away. Let the wind be a twenty-five 
mile breeze from the southwest. The wind alone tends to 
carry the balloon from New York to the point d in four 
hours. If the balloon meanwhile be headed due west, it 
would need an independent velocity of its own having the 
same ratio to that of the wind as that of de to fd 7 or about 
seventeen and one-half miles per hour. Suppose its inde- 



Air and the Wind 55 

pendent speed to be only twelve and one-half miles; then 
after four hours it will be at the position b, assuming 
it to have been continually headed due west, as indicated 




Count Zeppelin 



at a. It will have traveled northward the distance fe, 
apparently about sixty-nine miles. 

After this four hours of flight, the wind suddenly changes 
to south-southwest. It now tends to carry the balloon to 



56 Flying Machines Today 

g in the next four hours. Meanwhile the balloon, heading 
west, overcomes the easterly drift, and the balloon actually 
lands at c. Unless there is some further favorable shift 
of the wind it cannot reach Albany. If, during the second 
four hours, its independent speed could have been increased 
to about fifteen and a half miles it would have just made it. 
The actual course has been fbc : a drifting balloon would 
have followed the course fdh, dh being a course parallel 
to bg. 



GAS AND BALLAST 



A cubical block of wood measuring twelve inches on a 
side floats on water because it is lighter than water; it 
weighs, if yellow pine, thirty-eight pounds, whereas the 
same volume of water weighs about sixty- two pounds. 
Any substance weighing more than sixty-two pounds to 
the cubic foot would sink in water. 



Drilled Hole, 
Plugged with Lead 




Buoyant Power of Wood 

If our block of wood be drilled, and lead poured in the 
hole, the total size of wood-and-lead block being kept con- 
stantly at one cubic foot, the block will sink as soon as its 
whole weight exceeds sixty- two pounds. Ignoring the 
wood removed by boring (as, compared with the lead 
which replaces it, an insignificant amount), the weight of 
lead plugged in may reach twenty-four pounds before the 
block will sink. 

This figure, twenty-four pounds, the difference between 

57 



58 Flying Machines Today 

sixty-two and thirty-eight pounds, then represents the 
maximum buoyant power of a cubic foot of wood in water. 
It is the difference between the weight of the wood block 
and the weight of the water it displaces. If any weight 




:t 

3.1 Inches out 
of Water 



Just immersed 



One Cubic Foot of Wood Loaded in Water 

less than this is added to that of the wood, the block will 
float, projecting above the water's surface more or less, 
according to the amount of weight buoyed up. It will not 
rise entirely from the water, because to do this it would 
need to be lighter, not only than water, but than air. 



Buoyancy in Air 

There are gases, if not woods, lighter than air: among 
them, coal gas and hydrogen. A "bubble" of any of these 
gases, if isolated from the surrounding atmosphere, cannot 
sink but must rise. At the same pressure and tempera- 
ture, hydrogen weighs about one-fifteenth as much as air; 
coal gas, about one-third as much. If a bubble of either 
of these gases be isolated in the atmosphere, it must con- 
tinually rise, just as wood immersed in water will rise when 



Gas and Ballast 



59 



liberated. But the wood will stop when it reaches the sur- 
face of the water, while there is no reason to suppose that 
the hydrogen or coal gas bubbles will ever stop. The hydro- 
gen bubble can be made to remain stationary if it is weighted 
down with something of about fourteen times its own 
weight (thirteen and one-half times, accurately). Perhaps 
it would be better to say that it would still continue to rise 




z> 



Yt Pounds 
of Lead 



Buoyant Power of Hydrogen 



slowly because that additional something would itself dis- 
place some additional air; but if the added weight is a 
solid body, its own buoyancy in air is negligible. 

Our first principle is, then, that at the same pressure 
and temperature, any gas lighter than air, if properly 
confined, will exert a net lifting power of (n — i) times 
its own weight, where n is the ratio of weights of air and 
gas per cubic foot. 

If the pressures and temperatures are different, this 
principle is modified. In a balloon, the gas is under a 



Gas and Ballast 61 

pressure slightly in excess of that of the external atmos- 
phere: this decreases its lifting power, because the weight 
of a given volume of gas is greater as the pressure to which 
it is subjected is increased. The weight of a given volume 
we have called the density : and, as has been stated, if the 
temperature be unchanged, the density varies directly as 
the pressure. 

The pressure in a balloon is only about i% greater than 
that of the atmosphere at sea level, so that this factor has 
only a slight influence on the lifting power. That it leads 
to certain difficulties in economy of gas will, however, soon 
be seen. 

The temperature of the gas in a balloon, one might 
think, would naturally be the same as that of the air out- 
side: but the surface of the balloon envelope has an absorb- 
ing capacity for heat, and on a bright sunny day the gas 
may be considerably warmed thereby. This action in- 
creases the lifting power, since increase of temperature 
(the pressure remaining fixed) decreases the density of a 
gas. To avoid this possibly objectionable increase in 
lifting power, balloons are sometimes painted with a non- 
absorbent color. One of the first Lebaudy balloons re- 
ceived a popular nickname in Paris on account of the yellow 
hue of its envelope. 

Suppose we wish a balloon to carry a total weight, 
including that of the envelope itself, of a ton. If of hydro- 
gen, it will have to contain one fifteenth of this weight or 
about 133 pounds of that gas, occupying a space of about 



62 Flying Machines Today 

23,000 cubic feet. If coal gas is used, the size of the 
balloon would have to be much greater. If hot air is used 
— as has sometimes been the case — let us assume the 
temperature of the air inside the envelope such that the 
density is just half that of the outside air. This would 
require a temperature probably about 500 . The air 




(Photo by Paul Thompson, N.Y.) 

Air Balloon 
Built by some Germans in the backwoods of South Africa 



needed would be just a ton, and the balloon would be 
of about 52,000 cubic feet. It would soon lose its lifting 
power as the air cooled; and such a balloon would be 
useful only for short flights. 

The 23,000 cubic foot hydrogen balloon, designed to 
carry a ton, would just answer to sustain the weight. If 



Gas and Ballast 6$ 

anchored at sea level, it would neither fall to the ground 
nor tug upward on its holding-down ropes. In order to 
ascend, something more is necessary. This ''something 
more" might be some addition to the size and to the 
amount of hydrogen. Let us assume that we, instead, drop 
one hundred pounds of our load. Thus relieved of so much 
ballast, the balloon starts upward, under the net lifting 
force of one hundred pounds. It is easy to calculate how 
far it will go. It will not ascend indefinitely, because, as 
the altitude increases, the pressure (and consequently the 
density) of the external atmosphere decreases. At about 
a 2000-foot elevation, this decrease in density will have 
been sufficient to decrease the buoyant power of the hydro- 
gen to about 1900 pounds, and the balloon will cease to 
rise, remaining at this level while it moves before the 
wind. 

There are several factors to complicate any calculations. 
Any expansion of the gas bag — stretching due to an in- 
crease in internal pressure — would be one; but the envelope 
fabrics do not stretch much; there is indeed a very good 
reason why they must not be allowed to stretch. The 
pressure in the gas bag is a factor. If there is no stretching 
of the bag, this pressure will vary directly with the tem- 
perature of the gas, and might easily become excessive 
when the sun shines on the envelope. 

A more serious matter is the increased difference between 
the internal pressure of the gas and the external pressure 
of the atmosphere at high altitudes. Atmospheric pres- 



64 Flying Machines Today 

sure decreases as we ascend. The difference between gas 
pressure and air pressure thus increases, and it is this 
difference of pressure which tends to burst the envelope. 
Suppose the difference of pressure at sea level to have 
been two-tenths of a pound. For a balloon of twenty feet 
diameter, this would give a stress on the fabric, per lineal 
inch, of twenty-four pounds. At an altitude of 2000 feet, 
the atmospheric pressure would decrease by one pound, 
the difference of pressures would become one and two-tenths 
pounds, and the stress on the fabric would be 144 pounds 
per lineal inch — an absolutely unpermissible strain. 
There is only one remedy: to allow some of the gas to 
escape through the safety valve; and this will decrease our 
altitude. 

Ascending and Descending 

To ascend, then, we must discard ballast: and we can- 
not ascend beyond a certain limit on account of the limit 
of allowable pressure on the envelope fabric. To again 
descend, we must discharge some of the gas which gives 
us lifting power. Every change of altitude thus involves 
a loss either of gas or of ballast. Our vertical field of 
control may then be represented by a series of oscillations 
of gradually decreasing magnitude until finally all power 
to ascend is gone. And even this situation, serious as it 
is, is made worse by the gradual but steady leakage of 
gas through the envelope fabric. Here, in a word, is the 
whole problem of altitude regulation. Air has no surface 



Gas and Ballast 65 

of equilibrium like water. Some device supplementary to 
ballast and the safety valve is absolutely necessary for 
practicable flight in any balloon not staked to the ground. 

A writer of romance has equipped his aeronautic heroes 
with a complete gas-generating plant so that all losses 
might be made up; and in addition, heating arrangements 
were provided so that when the gas supply had been par- 
tially expended its lifting power could be augmented by 
warming it so as to decrease its density below even the 
normal. There might be something to say in favor of 
this latter device, if used in connection with a collapsible 
gas envelope. 

Methods of mechanically varying the size of the balloon, 
so as by compressing the gas to cause descent and by giving 
it more room to increase its lifting power and produce 
ascent, have been at least suggested. The idea of a vacuum 
balloon, in which a rigid hollow shell would be exhausted 
of its contents by a continually working pump, may appear 
commendable. Such a balloon would have maximum 
lifting power for its size; but the weight of any rigid shell 
would be considerable, and the pressure tending to rupture 
it would be about 100 times that in ordinary gas balloons. 

It has been proposed to carry stored gas at high pressure 
(perhaps in the liquefied condition) as a supplementary 
method of prolonging the voyage while facilitating vertical 
movements : but hydrogen gas at a pressure of a ton to the 
square inch in steel cylinders would give an ultimate lift- 
ing power of only about one-tenth the weight of the cylin- 



66 Flying Machines Today 

ders which contain it. These cylinders might be regarded 
as somewhat better than ordinary ballast: but to throw 
them away, with their gas charge, as ballast, would seem 
too tragic. Liquefied gas might possibly appear rather 
more desirable, but would be altogether too expensive. 

If a screw propeller can be used on a steamship, a dirigible 
balloon, or an aeroplane to produce forward motion, there 
is no reason why it could not also be used to produce up- 
ward motion in any balloon; and the propeller with its 



£ 



Equilibrating Propeller 



A TT 



^Engine 



t 



^Propeller 
Gears 



Equilibrating Propeller 



Screw Propeller for Altitude Control 

operating machinery would be a substitute for twice its 
equivalent in ballast, since it could produce motion either 
upward or downward. Weight for weight, however, the 
propeller and engine give only (in one computed case) 
about half the lifting power of hydrogen. If we are to use 
the screw for ascent, we might well use a helicopter, heavier 
than air, rather than a balloon. 

The Ballonet 

The present standard method of improving altitude 
regulation involves the use of the ballonet, or compartment 



Gas and Ballast 67 

air bag, inside the main envelope. For stability and 
effective propulsion, it is important that the balloon pre- 
serve its shape, no matter how much gas be allowed to 
escape. Dirigible balloons are divided into two types, 
according to the method employed for maintaining the 
shape. In the Zeppelin type, a rigid internal metal frame- 
work supports the gas envelope. This forms a series of 
seventeen compartments, each isolated from the others. 
Xo matter what the pressure of gas, the shape of the 
balloon is unchanged. 

In the more common form of balloon, the internal 
air ballonet is empty, or nearly so, when the main 
envelope is full. As gas is vented from the latter, 
air is pumped into the former. This compresses the 
remaining gas and thus preserves the normal form cf the 
balloon outline. 

But the air ballonet does more than this. It provides 




^Air Valves 
Balloon with Ballonets 



an opportunity for keeping the balloon on a level keel, 
for by using a number of compartments the air can be 
circulated from one to another as the case may require, 
thus altering the distribution of weights. Besides this, if 



68 



Flying Machines Today 




Gas and Ballast 



6 9 



the pressure in the air ballonet be initially somewhat 
greater than that of the external atmosphere, a consider- 
able ascent may be produced by merely venting this air 
ballonet. This involves no loss of gas; and when it is 
again desired to descend, air may be pumped into the bal- 
lonet. If any considerable amount of gas should be 
vented, to produce quick and rapid descent, the pumping 
of air into the ballonet maintains the shape of the balloon 
and also facilitates the descent. 



The Equilibrator 

Suppose a timber block of one square foot area, ten feet 
long, weighing 380 pounds, to be suspended from the 





<^^ Balloon ~^> 


,A A. ^ 


, 






Timber Bloct I2x 12x KM)" 
380 lbs. 




^ 


7 /^^ 


JSHBiifi 




Jtt^mmT 


— 


Vr= 




I 6.09 f t.Immersed 


! gives Equilibrium 
1 j 







The Equilibrator in Neutral Position 

balloon in the ocean, and let mechanism be provided by 
which this block may be raised or lowered at pleasure. 
When completely immersed in water it exerts an upward 



70 Flying Machines Today 

pressure (lifting force) of 240 pounds, which may be used 
to supplement the lifting power of the balloon. If wholly 
withdrawn from the water, it pulls down the balloon with 
its weight of 380 pounds. It seems to be equivalent, there- 
fore, to about 620 pounds of ballast. When immersed a 
little over six feet — the upper four feet being out of the 
water — it exerts neither lifting nor depressing effect. 
The amount of either may be perfectly adjusted between 
the limits stated by varying the immersion. 

In the Wellman-Vaniman equilibrator attached to the 
balloon America, which last year carried six men (and a cat) 
a thousand miles in three days over the Atlantic Ocean, a 
string of tanks partly filled with fuel was used in place of 
the timber block. As the tanks were emptied, the degree 
of control was increased; and this should apparently 
have given ideal results, equilibration being augmented as 
the gas supply was lost by leakage: but the unsailorlike 
disregard of conditions resulting from the strains trans- 
ferred from a choppy sea to the delicate gas bag led to 
disaster, and it is doubtful whether this method of control 
can ever be made practicable. The America's trip was 
largely one of a drifting rather than of a dirigible balloon. 
The equilibrator could be used only in flights over water 
in any case : and if we are to look to water for our buoyancy, 
why not look wholly to water and build a ship instead 
of a balloon? 



DIRIGIBLE BALLOONS AND OTHER KINDS 

Shapes 

The cylindrical Zeppelin balloon with approximately 
conical ends has already been shown (page 68). Those 
balloons in which the shape is maintained by internal 




Hexry Giffard's Dirigible 
(The first with steam power) 

pressure of air are usually pisciform, that is, fish-shaped. 
Studies have actually been made of the contour lines of 
various fishes and equivalent symmetrical forms derived, 

71 



72 



Flying Machines Today 



the outline of the balloon being formed by a pair of 
approximately parabolic curves. 

The first flight in a power driven balloon was made by 
Giffard in 1852. This balloon had an independent speed 
of about ten feet per second, but was without appliances 




Dirigible of Dupuy de Lome 
(Man Power) 



for steering. A ballonetted balloon of 120,000 cubic feet 
capacity was directed by man power in 1872: eight men 
turned a screw thirty feet in diameter which gave a speed 
of about seven miles per hour. Electric motors and 
storage batteries were used for dirigible balloons in 1883- 
'84: in the latter year, Renard and Krebs built the first 



Dirigible Balloons and Other Kinds 



73 




Tlssaivdler Brothers' Dirigible Balloon 
(Electric Motor) 

fish-shaped balloon. The first dirigible driven by an 
internal combustion motor was used by Santos-Dumont 
in 1901. 

Dimensions 

The displacements of present dirigibles vary from 20,000 
cubic feet (in the United States Signal Corps airship) up 
to 460.000 cubic feet (in the Zeppelin) . The former balloon 
has a earning capacity only about equivalent to that of 
a Wright biplane. While anchored or drifting balloons 
are usually spherical, all dirigibles are elongated, with a 
length of from four to eleven diameters. The Zeppelin 
represents an extreme elongation, the length being 450 
feet and the diameter fortv-two feet. At the other extreme, 



74 Flying Machines Today 

some of the English military dirigibles are thirty-one feet 
in diameter and only 112 feet long. Ballonet capacities 
may run up to one-fifth the gas volume. All present 
dirigibles have gasoline engines driving propellers from 




The Baldwin 
Dirigible of the United States Signal Corps 

eight to twenty feet in diameter. The larger propellers 
are connected with the motors by gearing, and make from 
250 to 700 turns per minute. The smaller propellers are 
direct connected and make about 1 200 revolutions. Speeds 
are usually from fifteen to thirty miles per hour. 

The present-day elongated shape is the result of the effort 



Dirigible Balloons and Other Kinds 



75 




76 Flying Machines Today 

to decrease the proportion of propulsion resistance due to 
the pressure of the air against the head of the balloon. 
This has led also to the pointed ends now universal; and to 
avoid eddy resistance about the rear it is just as important 
to point the stern as the bow. As far as head end resistance 
alone is concerned, the longer the balloon the better: but 
the friction of the air along the side of the envelope also 
produces resistance, so that the balloon must not be too 
much elongated. Excessive elongation also produces 
structural weakness. From the standpoint of stress on the 
fabric of the envelope, the greatest strain is that which 
tends to break the material along a longitudinal line, and 
this is true no matter what the length, as long as the seams 
are equally strong in both directions and the load is so 
suspended as not to produce excessive bending strain on 
the whole balloon. In the Pa trie (page 77), some dis- 
tortion due to loading is apparent. The stress per lineal 
inch of fabric is obtained by multiplying the net pressure 
by half the diameter of the envelope (in inches) . 

Ample steering power (provided by vertical planes, as 
in heavier-than-air machines) is absolutely necessary in 
dirigibles: else the head could not be held up to the wind 
and the propelling machinery would become ineffective. 

Fabrics 

The material for the envelope and ballonets should be 
light, strong, unaffected by moisture or the atmosphere, 
non-cracking, non-stretching, and not acted upon by varia- 






78 Flying Machines Today 

tions in temperature. The same specifications apply to 
the material for the wings of an aeroplane. In addition, 
for use in dirigible balloons, fabrics must be impermeable, 
resistent to chemical action of the gas, and not subject to 
spontaneous combustion. The materials used are vulcan- 
ized silk, gold beater's skin, Japanese silk and rubber, and 
cotton and rubber compositions. In many French balloons, 
a middle layer of rubber has layers of cotton on each side, 
the whole thickness being the two hundred and fiftieth 
part of an inch. In the Patrie, this was supplemented by 
an outside non-heat-absorbent layer of lead chromate and 
an inside coating of rubber, all rubber being vulcanized. 
The inner rubber layer was intended to protect the fabric 
against the destructive action of impurities in the gas. 

Fabrics are obtainable in various colors, painted, var- 
nished, or wholly uncoated. The rubber and cotton mix- 
tures are regularly woven in France and Germany for 
aeroplanes and balloons. The cars and machinery are 
frequently shielded by a fabricated wall. Weights of 
envelope materials range from one twenty-third to one- 
fourteenth pound per square foot, and breaking stresses 
from twenty-eight to one hundred and thirty pounds. 
Pressures (net) in the main envelope are from three-fifths 
to one and a quarter ounces per square inch, those in the 
ballonets being somewhat less. The Patrie of 1907 had an 
envelope guaranteed not to allow the leakage of more 
than half a cubic inch of hydrogen per square foot of sur- 
face per twenty-four hours. 



Dirigible Balloons and Other Kinds 81 

The best method of cutting the fabric is to arrange for 
building up the envelope by a series of strips about the cir- 
cumference, the seams being at the bottom. The two 
warps of the cloth should cross at an angle so as to localize 
a rip or tear. Bands of cloth are usually pasted over the 
seams, inside and out, with a rubber solution; this is to 
prevent leakage at the stitches. 

Framing 

In the Zeppelin, the rigid aluminum frame is braced 
every forty-five feet by transverse diametral rods which 
make the cross-sections resemble a bicycle wheel (page 68). 
This cross-section is not circular, but sixteen-sided. The 
pressure is resisted by the framework itself, the envelope 
being required to be impervious only. The seventeen com- 
partments are separated by partitions of sheet aluminum. 
There is a system of complete longitudinal bracing between 
these partitions. Under the main framework, the cars and 
machinery are carried by a truss about six feet deep which 
runs the entire length. The cars are boat-shaped, twenty 
feet long and six feet wide, three and one-half feet high, 
enclosed in aluminum sheathing. These cars, placed about 
one hundred feet from the ends, are for the operating force 
and machinery. The third car, carrying passengers, is 
built into the keel. 

In non-rigid balloons like the Patrie, the connecting 
frame must be carefully attached to the envelope. In this 
particular machine, cloth flaps were sewed to the bag, and 



Dirigible Balloons and Other Kinds 83 

nickel steel tubes then laced in the flaps. With these 
tubes as a base, a light framework of tubes and wires, 
covered with a laced-on waterproof cloth, was built up for 
supporting the load. Braces ran between the various 
stabilizing and controlling surfaces and the gas bag; these 
were for the most part very fine wire cables. The weight 
of the car was concentrated on about seventy feet of the 
total length of 200 feet. This accounts for the deformation 
of the envelope shown in the illustration (page 77). The 
frame and car of this balloon were readily dismantled for 
transportation. 

In some of the English dirigibles the cars were suspended 
by network passing over the top of the balloon. 

Keeping the Keel Horizontal 

In the Zeppelin, a sliding weight could be moved along 
the keel so as to cause the center of gravity to coincide with 
the center of upward pressure in spite of variations in 
weight and position of gas, fuel, and ballast. In the Ger- 
man balloon Parseval, the car itself was movable on a 
longitudinal suspending cable which carried supporting 
sheaves. This balloon has figured in recent press notices. 
It was somewhat damaged by a collision with its shed in 
March: the sixteen passengers escaped unharmed. A few 
days later, emergency deflation by the rip-strip was made 
necessary during a severe storm. In the ordinary non-rigid 
balloon, the pumping of air between the ballonets aids in 
controlling longitudinal equilibrium. The pump may be 



Dirigible Balloons and Other Kinds 85 

arranged for either hand or motor operation: that in the 
Clement-Bayard had a capacity of 1800 liters per minute 
against the pressure of a little over three-fifths of an ounce. 
The Parseval has two ballonets. Into the rear of these air 
is pumped at starting. This raises the bow and facilitates 
ascent on the principle of the inclined surface of an aero- 
plane. After some elevation is attained, the forward bal- 

lonet is also rilled. 

Stability 

Besides proper distribution of the loads, correct vertical 
location of the propeller is important if the balloon is to 
travel on a level keel. In some early balloons, two envel- 
opes side by side had the propeller at the height of the axes 
of the gas bags and midway between them. The modern 
forms carry the car, motor, and propeller below the balloon 
proper. The air resistance is mostly that of the bow of the 
envelope : but there is some resistance due to the car, and 
the propeller shaft should properly be at the equivalent 
center of all resistance, which will be between car and axis 
of gas bag and nearer the latter than the former. With a 
single envelope and propeller, this arrangement is imprac- 
ticable. By using four (or even two) propellers, as in the 
Zeppelin machine (page 68), it can be accomplished. If 
only one propeller is employed, horizontal rudder planes 
must be disposed at such angles and in such positions as to 
compensate for the improper position of the tractive force. 
Even on the Zeppelin, such planes were employed with 
advantage (pages 66 and 73). 



86 



Flying Machines Today 



Perfect stability also involves freedom from rolling. 
This is usually inherent in a balloon, because the center of 
mass is well below the center of buoyancy : but in machines 
of the non-rigid type the absence of a ballonet might lead 




Stern View or the Zeppelin 



to both rolling and pitching when the gas was partially 
exhausted. 

What is called " route stability" describes the condition 
of straight flight. The balloon must point directly in its 
(independent) course. This involves the use of a steering 



Dirigible Balloons and Other Kinds 87 

rudder, and, in addition, of fixed vertical planes, which, on 
the principle of the vertical partitions of Voisin, probably 
give some automatic steadiness to the course. To avoid 
the difficulty or impossibility of holding the head up to 
the wind at high speeds, an empennage or feathering tail 




The "Clement-Bayard" 

is a feature of all present balloons. The empennage of the 
Patrie (page 77) consisted of pairs of vertical and horizon- 
tal planes at the extreme stern. In the France, thirty-two 
feet in maximum diameter and nearly 200 feet long, em- 
pennage planes aggregating about 400 square feet were 
placed somewhat forward of the stern. In the Clement- 



Dirigible Balloons and Other Kinds 



8 9 



Bayard, the empennage consisted of cylindro-conical bal- 
lonets projecting aft from the stern. A rather peculiar 
grouping of such ballonets was used about the prolonged 
stern of the Ville de Paris. 



Rudders and Planes 

The dirigible has thus several air-resisting or gliding 
surfaces. The approximately "horizontal" (actually some- 




Car or THE "Liberte" 

what inclined) planes permit of considerable ascent and 
descent by the expenditure of power rather than gas, and 
thus somewhat influence the problem of altitude control. 
Each of the four sets of horizontal rudder planes on the 
Zeppelin, for example, has, at thirty-five miles per hour, 



90 Flying Machines Today 

with an inclination equal to one-sixth a right angle, a 
lifting power of nearly a ton; about equal to that of all 
of the gas in one of the sixteen compartments. 

Movable rudders may be either hand or motor-operated. 
The double vertical steering rudder of the Ville de Paris 
had an area of 150 square feet. The horizontally pivoted 
rudders for vertical direction had an area of 130 square 
feet. 

Arrangement and Accessories 

The motor in the Ville de Paris was at the front of the 
car, the operator behind it. This car had the excessive 
weight of nearly 700 pounds. The Patrie employed a non- 
combustible shield over the motor, for the protection of the 
envelope: its steering wheel was in front and the motor 
about in the middle of the car. The gasoline tank was 
under the car, compressed air being used to force the 
fuel up to the motor, which discharged its exhaust down- 
ward at the rear through a spark arrester. Motors have 
battery and magneto ignition and decompression cocks, 
and are often carried on a spring-supported chassis. The 
interesting Parseval propeller has four cloth blades which 
hang limp when not revolving. When the motor is run- 
ning, these blades, which are weighted with lead at the 
proper points, assume the desired form. 

Balloons usually carry guide ropes at head and stern, 
the aggregate weight of which may easily exceed a hundred 
pounds. In descending, the bow rope is first made fast, 
and the airship then stands with its head to the wind, to be 



Dirigible Balloons and Other Kinds 91 

hauled in by the stern rope. For the large French military 
balloons, this requires a force of about thirty men. The 
Zeppelin descends in water, being lowered until the cars 
float, when it is docked like a ship (see page 84). Land- 
ing skids are sometimes used, as with aeroplanes. 

The balloon must have escape valves in the main envelope 
and ballonets. In addition it has a "rip-strip" at the bot- 
tom by which a large cut can be made and the gas quickly 
vented for the purpose of an emergency descent. Common 
equipment includes a siren, megaphone, anchor pins, fire 
extinguisher, acetylene search light, telephotographic appa- 
ratus, registering and indicating gages and other instru- 
ments, anemometer, possibly carrier pigeons; besides fuel, 
oil and water for the motor, and the necessary supplies for 
the crew. The glycerine floated compass of Moisant must 
now also be included if we are to contemplate genuine 
navigation without constant recourse to landmarks. 

Amateur Dirigibles 

The French Zodiac types of " aerial runabout 1 ' displace 
700 cubic meters, carrying one passenger with coal gas or 
two passengers with a mixture of coal gas and hydrogen. 
The motor is four-cylinder, sixteen horse-power, water- 
cooled. The stern screw, of seven feet diameter, makes 
600 turns per minute, giving an independent speed of 
nineteen miles per hour. The machine can remain aloft 
three hours with 165 pounds of supplies. It costs S5000. 
Hydrogen costs not far from a cent per cubic foot (twenty 



9 2 



Flying Machines Today 




The Zodiac No. 2 
May be deflated and easily transported 

cents per cubic meter) so that the question of gas leakage 
may be at least as important as the tire question with 
automobiles. 

The Fort Omaha Plant 

The Signal Corps post at Fort Omaha has a plant com- 
prising a steel balloon house of size sufficient to house one 
of the largest dirigibles built, an electrolytic plant for 
generating hydrogen gas, having a capacity of 3000 cubic 
feet per hour, a 50,000 cubic foot gas storage tank, and 
the compressing and carrying equipment involved in pre- 
paring gas for shipment at high pressure in steel cylinders. 



Dirigible Balloons and Other Kinds 



93 




94 Flying Machines Today 

Balloon Progress 

The first aerial buoy of Montgolfier brothers, in 1783, 
led to the suggestion of Meussier that two envelopes be 
used; the inner of an impervious material to prevent gas 
leakage, and the outer for strength. There was perhaps 




The "Caroline" of Robert Brothers, 1784 
The ascent terminated tragically 

a foreshadowing of the Zeppelin idea. Captive and drift- 
ing balloons were used during the wars of the French 
Revolution: they became a part of standard equipment 
in our own War of Secession and in the Franco-Prussian 
conflict. The years 1906 to 1908 recorded rapid progress 
in the development of the dirigible: the record-breaking 
Zeppelin trip was in 1909 and Wellman's America exploit 



Dirigible Balloons and Other Kinds 



95 




The Ascent at Versailles, 1783 
The first balloon carrying living beings in the air 



9 6 



Flying Machines Today 



in October, 1910. Unfortunately, dirigibles have had a 
a bad record for stanchness: the Patrie, Republique, 
Zeppelin (I and i7) , Deutschland, Clement-Bayard — all 
have gone to that bourne whence no balloon returns. 




SOUSCRIFTIOW 



d* 200 Billets de 50 Francs 

naur /'Experience d'unMufioit dir/yea w>lou/e aiftnoi/en de dettj? 
a twnt placet dam- la nacelle et&uifanten avant dettx bmlei* .tuy 
rvu d'an BALLON 'enfomtr lie JPMMVW. 

Messieurs les Souscnplevm ««/ rembmwges tie tear-* avaneet 



hi >(h/f.\'rri/ rJtt'x Jf* '/■ ilhen 
' , /«•. t/'Orfeatu . f "•' /£ ./<7tJ' . 



vhr,/„. 

r /in, I 



fcMfew. 



f/,rr. 



Investors were lacking to bring about the realization of this project 



It is gratifying to record that Count Zeppelin's latest 
machine, the Deutschland II, is now in operation. During 
the present month (April, 191 1), flights have been made 
covering 90 miles and upward at speeds exceeding 20 miles 



98 Flying Machines Today 

per hour with the wind unfavorable. This balloon is in- 
tended for use as a passenger excursion vehicle during the 
coming summer, under contract with the municipality of 
Dtisseldorf. 

At the present moment, Neale, in England, is reported 
to be building a dirigible for a speed of a hundred miles per 
hour. The Siemens-Schuckart non-rigid machine, nearly 
400 feet long and of 500 horse-power, is being tried out at 
Berlin: it is said to carry fifty passengers.* Fabrice, of 
Munich, is experimenting with the Inchard, with a view to 
crossing the Atlantic at an early date. Mr. Vaniman, 
partner of Wellman on the America expedition, is planning 
a new dirigible which it is proposed to fly across the ocean 
before July 4. The engine, according to press reports, 
will develop 200 horse-power, and the envelope will be 
more elongated than that of the America. And meanwhile 
a Chicago despatch describes a projected fifty-passenger 
machine, to have a gross lifting power of twenty-five tons ! 

Germany has a slight lead in number of dirigible balloons 
— sixteen in commission and ten building. France fol- 
lows closely with fourteen active and eleven authorized. 
This accounts for two-thirds of all the dirigible balloons in 
the world. Great Britain, Italy, and Russia rank in the 
order named. The United States has one balloon of the 
smallest size. Spain has, or had, one dirigible. As to 



* According to press reports, temporary water ballast will be taken on 
during the daytime, to offset the ascensional effect of the hot sun on the 
envelope. 



Dirigible Balloons and Other Kinds 



99 





W -~=nk Lahm (Amer?) 








% Yam*, (er (Ir3i-) 










^ Henc 


aulx 




LONDRES 










5 


Hijiitingtcn 



fcnyUusm 



<S 



Von Abercroi 




PARIS 

The First Flight for the Gordox-Bexxet Cup. 
Won by Lieut. Frank P. Lahm, U.S.A.. 1906. Figures on the map de- 
note distances in kilometers. The cup has been offered annually by Mr. 
James Gordon-Bennet for international competition under such conditions 
as may be prescribed by the International Aeronautic Federation. 



ioo Flying Machines Today 

aeroplanes, however, the United States and England rank 
equally, having each about one-fourth as many machines 
as France (which seems, therefore, to maintain a "four- 
power standard")- Germany, Russia, and Italy follow, 
in order, the United States. These figures include all 
machines, whether privately or nationally owned. Until 
lately, our own government operated but one aeroplane. 
A recent appropriation by Congress of $125,000 has led to 
arrangements for the purchase of a few additional bi- 
planes of the Wright and Curtiss types; and a training 
school for army officers has been regularly conducted at 
San Diego, CaL, during the past winter. The Curtiss 
machine to be purchased is said to carry 700 pounds of 
dead weight with a sail area of 500 square feet. It is 
completely demountable and equipped with pontoons. 



THE QUESTION OF POWER 

In the year 1810, a steam engine weighed something 
over a ton to the horse-power. This was reduced to about 
200 pounds in 1880. The steam-driven dirigible balloon 
of Giffard, in 1852, carried a complete power plant weigh- 
ing a little over 100 pounds per horse-power; about the 
weight of a modern locomotive. The unsuccessful Maxim 
flying machine of 1894 brought this weight down to less 
than 20 pounds. The gasoline engine on the original 
Wright machines weighed about 5 pounds to the horse- 
power; those on some recent French machines not far 
from 2 pounds. 

Pig iron is worth perhaps a cent a pound. An ordinary 
steam or gas engine may cost eight cents a pound ; a steam 
turbine, perhaps forty cents. A high grade automobile 
or a piano may sell for a dollar a pound; the Gnome aero- 
plane motor is priced at about twenty dollars a pound. 
This is considerably more than the price of silver. The 
motor and accessories account for from two-thirds to nine- 
tenths of the total cost of an aeroplane. 

A man weighing 150 pounds can develop at the outside 
about one-eighth of a horse-power. It would require 
1200 pounds of man to exert one horse -power. Consid- 
ered as an engine, then, a man is (weight for weight) only 



102 Flying Machines Today 

one six-hundredth as effective as a Gnome motor. In the 
original Wright aeroplane, a weight of half a ton was 
sustained at the expenditure of about twenty-five horse- 
power. The motor weight was about one-eighth of the 
total weight. If traction had been produced by man-power, 




The Gnome Motor 
(Aeromotion Company of America) 

30,000 pounds of man would have been necessary: thirty 
times the whole weight supported. 

Under the most favorable conditions, to support his 
own weight of 15c pounds (at very high gliding velocity 
and a slight angle of inclination, disregarding the weight 
of sails necessary), a man would need to have the strength 



The Question of Power 103 

of about fifteen men. Xo such thing as an aerial bicycle, 
therefore, appears possible. The man can not emulate 
the bird. 



1 
1 

o 
U 



z < 



The power plant of an air craft includes motor, water 
and water tank, radiator and piping, shaft and bearings, 



104 



Flying Machines Today 



propeller, controlling wheels and levers, carbureter, fuel, 
lubricating oil and tanks therefor. Some of the weight may 
eventually be eliminated by employing a two-cycle motor 
(which gives more power for its size) or by using rotary 
air-cooled cylinders. Propellers are made light by employ- 
ing wood or skeleton construction. One eight-foot screw of 




One or the Motors oe the Zeppelin 

white oak and spruce, weighing from twelve to sixteen 
pounds, is claimed to give over 400 pounds of propelling 
force at a thousand turns per minute. 

The cut shows the action of the so-called " four-cycle" 
motor. Four strokes are required to produce an impulse 
on the piston and return the parts to their original posi- 



The Question oj Power 



i°5 



3 







IP 
1 




|» * 








e 



i 



3 



A 



I w 



I a 








Action of the Four-Cycle Engine 



106 Flying Machines Today 

tions. On the first, or suction stroke, the combustible 
mixture is drawn into the cylinder, the inlet valve being 
open and the outlet valve closed. On the second stroke, 
both valves are closed and the mixture is highly compressed. 
At about the end of this stroke, a spark ignites the charge, 
a still greater pressure is produced in consequence, and the 
energy of the gas now forces the piston outward on its 
third or " working" stroke, the valves remaining closed. 
Finally, the outlet valve is opened and a fourth stroke 
sweeps the burnt gas out of the cylinder. 




In the " two-cycle" engine, the piston first moves to 
the left, compressing a charge already present in the cylin- 
der at F, and meanwhile drawing a fresh supply through 
the valve A and passages C to the space D. On the 
return stroke, the exploded gas in F expands, doing its 



The Question of Power 107 

work, while that in D is slightly compressed, the valve A 
being now closed. When the piston, moving toward the 
right, opens the passage E, the burnt gas rushes out. A 
little later, when the passage / is exposed, the fresh com- 
pressed gas in D rushes through C, B, and / to F. The oper- 
ation may now be repeated. Only two strokes have been 
necessary. The cylinder develops power twice as rapidly 
as before: but at the cost of some waste of gas, since the 
inlet (/) and outlet (E) passages are for a brief interval 
both open at once: a condition not altogether remedied by 
the use of a deflector at G. A two-cycle cylinder should 
give nearly twice the power of a four-cycle cylinder of the 
same size, and the two-cycle engine should weigh less, 
per horse-power; but it requires from 10 to 30% more 
fuel, and fuel also counts in the total weight. 

The high temperatures in the cylinder would soon make 
the cast-iron walls red-hot, unless the latter were artifi- 
cially cooled. The usual method of cooling is to make 
the walls hollow and circulate water through them. This 
involves a pump, a quantity ot water, and a " radiator" 
(cooling machine) so that the water can be used over and 
over again. To cool by air blowing over the surface of 
the cylinder is relatively ineffective: but has been made 
possible in automobiles by building fins on the cylinders 
so as to increase the amount of cooling surface. When the 
motors are worked at high capacity, or when two-cycle 
motors are used, the heat is generated so rapidly that this 
method of cooling is regarded as inapplicable. By rapidly 



108 Flying Machines Today 

rotating the cylinders themselves through the air, as in 
motors like the Gnome, air cooling is made sufficiently 
adequate, but the expenditure of power in producing this 
rotation has perhaps not been sufficiently regarded. 




Motor and Propeller 
(Detroit Aeronautic Construction Co.) 

Possible progress in weight economy is destined to be 
limited by the necessity for reserve motor equipment. 

The engine used is usually the four-cycle, single-acting, 
four-cylinder gasoline motor of the automobile, designed 



The -Question of Power 109 

for great lightness. The power from each cylinder of 
such a motor is approximately that obtained by dividing 
the square of the diameter in inches by the figure 2 J. 
Thus a five-inch cylinder should give ten horse-power 
— at normal piston speed. On account of friction losses 
and the wastefulness of a screw propeller, not more than 
half this power is actually available for propulsion. 

The whole power plant of the Clement-Bayard weighed 
about eleven pounds to the horse-power. This balloon 
was 184 feet long and 35 feet in maximum diameter, 
displacing about 100,000 cubic feet. It carried six pas- 
sengers, about seventy gallons of fuel, four gallons of 
lubricating oil, fifteen gallons of water, 600 pounds of 
ballast, and 130 pounds of ropes. The motor developed 
100 horse-power at a thousand revolutions per minute. 
About eight gallons of fuel and one gallon of oil were con- 
sumed per hour when running at the full independent 
speed of thirty-seven miles per hour. 

The Wellman balloon America is said to have consumed 
half a ton of gasoline per twenty-four hours : an eight days' 
supply was carried. The gas leakage in this balloon was 
estimated to have been equivalent to a loss of 500 pounds 
of lifting power per day. 

The largest of dirigibles, the Zeppelin, had two motors 
of 170 horse-power each. It made, in 1909, a trip of over 
800 miles in thirty-eight hours. 

The engine of the original Voisin cellular biplanes was 
an eight-cylinder Antoinette of fifty horse-power, set near 



no 



Flying Machines Today 




Two-Cylinder Opposed Engine. 
(From Aircraft) 




Four-Cylinder Vertical Engine 
(The Dean Manufacturing Co.) 



The Question of Power in 

the rear edge of the" lower of the main planes. The 
Wright motors are placed near the front edge. A twenty- 
five horse power motor at 1400 revolutions propelled 
the Fort Myer machine, which was built to carry two 
passengers, with fuel for a 125 mile flight: the total 
weight of the whole flying apparatus being about half 
a ton. 

The eight-cylinder Antoinette motor on a Farman bi- 
plane, weighing 175 pounds, developed thirty-eight horse- 
power at 1050 revolutions. The total weight of the ma- 
chine was nearly 1200 pounds, and its speed twenty-eight 
miles per hour. 

The eight-cylinder Curtiss motor on the June Bug was 
air cooled. This aeroplane weighed 650 pounds and made 
thirty-nine miles per hour, the engine developing twenty- 
five horse-power at 1200 turns. 

Resistance of Aeroplanes 

The chart on page 24 (see also the diagram of page 
23) shows that the lifting power of an aeroplane increases 
as the angle of inclination increases, up to a certain limit. 
The resistance to propulsion also increases, however: and 
the ratio of lifting power to resistance is greatest at a very 
small angle — about five or six degrees. Since the motor 
power and weight are ruling factors in design, it is impor- 
tant to fly at about this angle. The supporting force is 
then about two pounds, and the resistance about three- 
tenths of a pound, per square foot of sail area, if the veloc- 



ii2 Flying Machines Today 

ity is that assumed in plotting the chart: namely, about 
fifty-five miles per hour. 

But the resistance R indicated on pages 23 and 24 is not 
the only resistance to propulsion. In addition, we have 
the frictional resistance of the air sliding along the sail sur- 
face. The amount of this resistance is independent of the 
angle of inclination: it depends directly upon the area of 
the planes, and in an indirect way on their dimensions in 
the direction of movement. It also varies nearly with the 
square of the velocity. At any velocity, then, the addition 
of this frictional resistance, which does not depend on the 
angle of inclination, modifies our views as to the desirable 
angle: and the total resistance reaches a minimum (in pro- 
portion to the weight supported) when the angle is about 
three degrees and the velocity about fifty miles per hour. 

This is not quite the best condition, however. The skin 
friction does not vary exactly with the square of the veloc- 
ity: and when the true law of variation is taken into ac- 
count, it is found that the horse-power is a minimum at 
an angle of about five degrees and a speed of about forty 
miles per hour. The weight supported per horse-power 
may then be theoretically nearly a hundred pounds : and the 
frictional resistance is about one-third the direct pressure 
resistance. This must be regarded as the approximate 
condition of best effectiveness: not the exact condition, 
because in arriving at this result we have regarded the 
sails as square flat planes whereas in reality they are 
arched and of rectangular form. 



The Question of Power 113 

At the most effective condition, the resistance to pro- 
pulsion is only about one- tenth the weight supported. 
Evidently the air is helping the motor. 

Resistance of Dirigibles 

If the bow of a balloon were cut off square, its head end 
resistance would be that given by the rule already cited 
(page 19): one three-hundredth pound per square foot, 




Head End Shapes 

multiplied by the square of the velocity. But by pointing 
the bow an enormous reduction of this pressure is pos- 
sible. If the head end is a hemisphere (as in the English 
military dirigible), the reduction is about one- third. If 
it is a sharp cone, the reduction may be as much as four- 
fifths. Unless the stern is also tapered, however, there 
will be a considerable eddy resistance at that point. 

If head end resistance were the only consideration, then 
for a balloon of given diameter and end shape it would be 
independent of the length and capacity. The longer the 
balloon, the better. Again, since the volume of any solid 
body increases more rapidly than its surface (as the lin- 
ear dimensions are increased), large balloons would have 
a distinct advantage over small ones. The smallest 



ii4 Flying Machines Today 

dirigible ever built was that of Santos-Dumont, of about 
5000 cubic feet. 

Large balloons, however, are structurally weak: and 
more is lost by the extra bracing necessary than is gained 
by reduction of head end resistance. It is probable that 
the Zeppelin represents the limit of progress in this direc- 
tion; and even in that balloon, if it had not been that the 
adoption of a rigid type necessitated great structural 
strength, it is doubtful if as great a length would have been 
fixed upon, in proportion to the diameter. 

The frictional resistance of the air gliding along the sur- 
face of the envelope, moreover, invalidates any too arbi- 
trary conclusions. This, as in the aeroplane, varies nearly 
as the square of the velocity, and is usually considerably 
greater than the direct head end resistance. Should the 
steering gear break, however, and the wind strike the side 
of the balloon, the pressure of the wind against this greatly 
increased area would absolutely deprive it of dirigibility. 

A stationary, drifting, or " sailing" balloon may as well 
have the spherical as well as any other shape : it makes the 
wind a friend instead of a foe and requires nothing in the 
way of control other than regulation of altitude. 

Independent Speed and Time Table 

The air pressure, direct and frictional resistances, and 
power depend upon the relative velocity of flying machine 
and air. It is this relative velocity, not the velocity of 
the balloon as compared with a point on the earth's sur- 



n6 Flying Machines Today 

face, that marks the limit of progression. Hence the speed 
of the wind is an overwhelming factor to be reckoned with 
in developing an aerial time table. If we wish to travel 
east at an effective speed of thirty miles per hour, while the 
wind is blowing due west at a speed of ten miles, our ma- 
chine must have an independent speed of forty miles. 
On the other hand, if we wish to travel west, an independ- 
ent speed of twenty miles per hour will answer. 

Again, if the wind is blowing north at thirty miles per 
hour, and the minimum (relative) velocity at which an 
aeroplane will sustain its load is forty miles per hour, we 
cannot progress northward any more slowly than at sev- 
enty miles' speed. And we have this peculiar condition 
of things: suppose the wind to be blowing north at fifty 
miles per hour. The aeroplane designed for a forty mile 
speed may then face this wind and sustain itself while 
actually moving backward at an absolute speed (as seen 
from the earth) of ten miles per hour. 

We are at the mercy of the wind, and wind velocities 
may reach a hundred miles an hour. The inherent dis- 
advantage of aerial flight is in what engineers call its 
"low load factor." That is, the ratio of normal perform- 
ance required to possible abnormal performance necessary 
under adverse conditions is extremely low. To make a 
balloon truly dirigible throughout the year involves, at 
Paris, for example, as we have seen, a speed exceeding 
fifty-four miles per hour : and even then, during one- tenth 
the year, the effective speed would not exceed twenty miles 



n8 Flying Machines Today 

per hour. A time table which required a schedule speed 
reduction of 60% on one day out of ten would be obviously 
unsatisfactory. 

Further, if we aim at excessively high independent 
speeds for our dirigible balloons, in order to become inde- 
pendent of wind conditions, we soon reach velocities at 
which the gas bag is unnecessary: that is, a simple wing 
surface would at those speeds give ample support. The 
increased difficulty of maintaining rigidity of the envelope, 
and of steering, at the great pressures which would accom- 
pany these high velocities would also operate against the 
dirigible type. 

With the aeroplane, higher speed means less sail area 
for a given weight and a stronger machine. Much higher 
speeds are probable. We have already a safe margin as 
to weight per horse-power of motor, and many aeroplane 
motors are for stanchness purposely made heavier than 
they absolutely need to be. 

The Cost of Speed 

Since the whole resistance, in either type of flying ma- 
chine, is approximately proportional to the square of the 
velocity; and since horse-power (work) is the product of 
resistance and velocity, the horse-power of an air craft 
of any sort varies about as the cube of the speed. To 
increase present speeds of dirigible balloons from thirty 
to sixty miles per hour would then mean eight times as 
much horse-power, eight times as much motor weight, 



The Question of Power 119 

eight times as rapid a rate of fuel consumption, and (since 
the speed has been doubled) four times as rapid a con- 
sumption of fuel in proportion to the distance traveled. 
Either the radius of action must be decreased, or the weight 
of fuel carried must be greatly increased, if higher veloc- 
ities are to be attained. Present (independent) aeroplane 
speeds are usually about fifty miles per hour, and there is 
not the necessity for a great increase which exists with the 
lighter- than-air machines. We have already succeeded in 
carrying and propelling fifty pounds of total load or fifteen 
pounds of passenger load per horse-power of motor, with 
aeroplanes; the ratio of net load to horse power in the diri- 
gible is considerably lower; but the question of weight in 
relation to power is of relatively smaller importance in the 
latter machine, where support is afforded by the gas and 
not by the engine. 

The Propeller 

Very little effort has been made to utilize paddle wheels 
for aerial propulsion; the screw is almost universally em- 
ployed. Every one knows that when a bolt turns in a 
stationary nut, it moves forward a distance equal to the 
pitch (lengthwise distance between two adjacent threads) 
at every revolution. A screw propeller is a bolt partly 
cut away for lightness, and the "nut" in which it works 
is water or air. It does not move forward quite as much as 
its pitch, at each revolution, because any fluid is more or 
less slippery as compared with a nut of solid metal. The 
difference between the pitch and the actual forward move- 



120 Flying Machines Today 

ment of the vessel at each revolution is called the "slip," 
or "slip ratio." It is never less than ten or twelve per cent 
in marine work, and with aerial screws is much greater. 
Within certain limits, the less the slip, the greater the 
efficiency of the propeller. Small screws have relatively 
greater slips and less efficiency, but are lighter. The maxi- 
mum efficiency of a screw propeller in water is under 80%. 
According to Langley's experiments, the usual efficiency in 
air is only about 50%. This means that only half the power 
of the motor will be actually available for producing for- 
ward movement — a conclusion already foreshadowed. 

In common practice, the pitch of aerial screws is not 
far from equal to the diameter. The rate of forward move- 
ment, if there were no slip, would be proportional to the 
pitch and the number of revolutions per minute. If the 
latter be increased, the former may be decreased. Screws 
direct-connected to the motors and running at high speeds 
will therefore be of smaller pitch and diameter than those 
run at reduced speed by gearing, as in the machine illus- 
trated on page 134. The number of blades is usually two, 
although this gives less perfect balance than would a larger 
number. The propeller is in many monoplanes placed in 
front: this interferes, unfortunately, with the air currents 
against the supporting surfaces. 

There is always some loss of power in the bearings and 
power-transmitting devices between the motor and pro- 
peller. This may decrease the power usefully exerted 
even to less than half that developed by the motor. 



GETTING UP AND DOWN: MODELS AND 
GLIDERS: AEROPLANE DETAILS 

Launching 

The Wright machines (at least in their original form) 
have usually been started by the impetus of a falling weight, 
which propels them along skids until the velocity suffices 
to produce ascent. The preferred designs among French 
machines have contemplated self-starting equipment. 




Weight Biplane ox Starting Rail, showing Pylon and Weight 

This involves mounting the machine on pneumatic-tired 
bicycle wheels so that it can run along the ground. If a 
fairly long stretch of good, wide, straight road is avail- 
able, it is usually possible to ascend. The effect of alti- 
tude and atmospheric density on sustaining power is 
forcibly illustrated by the fact that at Salt Lake City 
one of the aviators was unable to rise from the ground. 

To accelerate a machine from rest to a given velocity 
in a given time or distance involves the use of propulsive 

121 



122 



Flying Machines Today 




Getting Up and Down 123 

force additional to that necessary to maintain the velocity 
attained. Apparently, therefore, any self-starting machine 
must have not only the extra weight of framework and 
wheels but also extra motor power. 

Upon closer examination of the matter, we may find a 
particularly fortunate condition of things in the aeroplane. 
Both sustaining power and resistance vary with the incli- 
nation of the planes, as indicated by the chart on page 24. 
It is entirely possible to start with no such inclination, so 
that the direct wind resistance is eliminated. The motor 
must then overcome only air friction, in addition to pro- 
viding an accelerating force. The machine runs along the 
ground, its velocity rapidly increasing. As soon as the 
necessary speed (or one somewhat greater) is attained, 
the planes are tilted and the aeroplane rises from the 
ground. 

The velocity necessary to just sustain the load at a 
given angle of inclination is called the critical or soaring 
velocity. For a given machine, there is an angle of incli- 
nation (about half a right angle) at which the minimum 
speed is necessary. This speed is called the "least soaring 
velocity." If the velocity is now increased, the angle of 
inclination may be reduced and the planes will soar through 
the air almost edgewise, apparently with diminished resist- 
ance and power consumption. This decrease in power 
as the speed increases is called Langley's Paradox, from 
its discoverer, who, however, pointed out that the rule 
does not hold in practice when frictional resistances are 



124 



Flying Machines Today 




Getting Up and Down 



125 



included. We cannot expect to actually save power by 
moving more rapidly than at present; but we should have 
to provide much more power if we tried to move much 
more slowly. 





A BlPLAXE 

(From Aircraft) 



I2( 



Flying Machines Today 



Economical and practicable starting of an aeroplane thus 
requires a free launching space, along which the machine 
may accelerate with nearly flat planes: a downward slope 
would be an aid. When the planes are tilted for ascent, 
after attaining full speed, quick control is necessary to 
avoid the possibility of a back-somersault. A fairly wide 



S- 




w 






* 

JL- If »*■" 


^%gp=- ^ i 


$Mt 


' 





(Photo by American Press Association) 

Ely at Los Angeles 

launching platform of 200 feet length would ordinarily 
suffice. The flight made by Ely in January of this year, 
from San Francisco to the deck of the cruiser Pennsylvania 
and back, demonstrated the possibility of starting from a 
limited area. The wooden platform built over the after 



Getting Up and Down 127 

deck of the warship was 130 feet long, and sloped. On 
the return trip, the aeroplane ran down this slope, dropped 
somewhat, and then ascended successfully. 

If the effort is made to ascend at low velocities, then the 
motor power must be sufficient to propel the machine at 
an extreme angle of inclination — perhaps the third of a 
right angle, approximating to the angle of least velocity 
for a given load. According to Chatley, this method of 
starting by Farman at Issy-les-Molineaux involved the 
use of a motor of fifty horse-power: while Roe's machine 
at Brooklands rose, it is said, with only a six horse-power 
motor. 

Descending 

What happens when the motor stops? The velocity 
of the machine gradually decreases: the resistance to 
forward movement stops its forward movement and the 




excess of weight over upward pressure due to velocity 
causes it to descend. It behaves like a projectile, but 
the details of behavior are seriously complicated by the 
variation in head resistance and sustaining force due to 



Getting Up and Down 129 

changes in the angle of the planes. The " angle of inclina- 
tion" is now not the angle made by the planes with the 
horizontal, but the angle which they make with the path 
of flight. Theory indicates that this should be about two- 
thirds the angle which the path itself makes with the 
horizontal: that is, the planes themselves are inclined 
downward toward the front. The forces which determine 
the descent are fixed by the velocity and the angle between 
the planes and the path of flight. Manipulation of the 
rudders and main planes or even the motor may be prac- 
tised to ensure lancing to best advantage; but in spite of 
these (or perhaps on account of these) scarcely any part 
of aviation offers more dangers, demands more genius on 
the part of the operator, and has been less satisfactorily 
analyzed than the question of "getting down." It is 
easy to stay up and not very hard to "get up," weather 
conditions being favorable; but it is an "all-sufficient 
job" to come down. Under the new rules of the Inter- 
national Aeronautic Federation, a test flight for a pilot's 
license must terminate with a descent (motor stopped) 
in which the aviator is to land within fifty yards of the 
observers and come to a full stop inside of fifty yards there- 
from. The elevation at the beginning of descent must 

be at least 150 feet. 

Gliders 

If the motor and its appurtenances, and some of the 
purely auxiliary planes, be omitted, we have a glider. The 
glider is not a toy; some of the most important problems 



130 Flying Machines Today 

of balancing may perhaps be some day solved by its aid. 
Any boy may build one and fly therewith, although a 
large kite promises greater interest. The cost is trifling, 
if the framework is of bamboo and the surfaces are cotton. 
Areas of glider surfaces frequently exceed 100 square feet. 
This amount of surface is about right for a person of mod- 




The Witteman Glider 

erate weight if the machine itself does not weigh over 
fifty pounds. By running down a slope, sufficient velocity 
may be attained to cause ascent; or in a favorable wind 
(up the slope) a considerable backward flight may be 
experienced. Excessive heights have led to fatal accidents 
in gliding experiments. 



Getting Up and Down 131 

Models 
The building of flying models has become of commercial 
importance. It is not difficult to attain a high ratio of 
surface to weight, but it is almost impossible to get motor 
power in the small units necessary without exceeding the 
permissible limit of motor weight. Xo gasoline engine 
or electric motor can be made sufficiently light for a toy 
model. Clockwork springs, if especially designed, may 
give the necessary power for short flights, but no better 
form of power is known just now than the twisted rubber 
band. For the small boy. a biplane with sails about 
eighteen inches by four feet, eighteen inches apart, 
anchored under his shoulders by six-foot cords while he 
rides his bicycle, will give no small amount of experience 
in balancing and will support enough of a load to make 
the experiment interesting. 

Some Details: Balancing 
It is easily possible to compute the areas, angles, and 
positions of auxiliary planes to give desired controlling or 
stabilizing effects; but the computation involves the use 
of accurate data as to positions of the various weights, and 
on the whole it is simpler to correct preliminary calcula- 
tions by actually supporting the machine at suitable 
points and observing its balance. Stability is especially 
uncertain at very small angles of inclination, and such angles 
are to be avoided whether in ordinary operation or in 



132 Flying Machines Today 

descent. The necessity for rotating main planes in order 
to produce ascent is disadvantageous on this ground; but 
the proposed use of sliding or jockey weights for supple- 






French Monoplane 
(From Aircraft) 

mentary balancing appears to be open to objections no 
less serious. Steering may be perceptibly assisted, in as 
delicately a balanced device as the aeroplane, by the 



Getting Up and Down 



J 33 



inclination of the body of the operator, just as in a bicycle. 
The direction of the wind in relation to the required course 
may seriously influence the steering power. Suppose the 
course to be northeast, the wind east, the independent 
speed of the machine and that of the wind being the same. 
The car will head due north. By bringing the rudder in 
position (a), the course may be changed to north, or 
nearly so, the wind exerting a powerful pressure on the 



Wind E. 




b Rudder position 

to make course E-X.E. 
(ineffective) 



^Rudder position 
to make course 
approximately X - X. E . 



rudder; but if a more easterly or east-northeast course 
be desired, and the rudder be thrown into the usual posi- 
tion therefor (b), it will exert no influence whatever, 
because it is moving before the wind and precisely at the 
speed of the wind. 

It might be thought that, following analogies of marine 
engineering, the center of gravity of an aeroplane should 
be kept low. The effect of any unbalanced pressure or 
force against the widely extended sails of the machine is 
to rotate the whole apparatus about its center of gravity. 



Getting Up and Down 135 

The further the force from the center of gravity, the more 
powerful is the force in producing rotation. The defect 
in most aeroplanes (especially biplanes) is that the center 
of gravity is too low. If it could be made to coincide with 
the center of disturbing pressure, there would be no un- 
balancing effect from the latter. It is claimed that the 
steadiest machines are those having a high center of grav- 
ity; and the claim, from these considerations, appears 
reasonable. 

Weights 

It has been found not difficult to keep down the weight 
of framework and supporting surfaces to about a pound 
per square foot. The most common ratio of surface to 




The Tellier Two-seat Six-cylinder Monoplane at the 

Paris Show 

One of this type has been sold to the Russian Government 

(From Aircraft) 

total weight is about one to two: so that the machinery 
and operator will require one square foot of surface for 
each pound of their weight. On this basis, the smallest 
possible man-carrying aeroplane would have a surface 



136 Flying Machines Today 

scarcely below 250 square feet. Most biplanes have twice 
this surface: a thousand square feet seems to be the 
limit without structural weakness. Some recent French 
machines, designed for high speeds, show a greatly in- 
creased ratio of weight to surface. The Hanriot, a mono- 
plane with wings upwardly inclined toward the outer 
edge, carries over 800 pounds on less than 300 square feet. 
The Farman monoplane of only 180 square feet sustains 
over 600 pounds. The same aviator's racing biplane is 
stated to support nearly 900 pounds on less than 400 
square feet. 

Motor weights can be brought down to about two pounds 
per horse-power, but such extreme lightness is not always 
needed and may lead to unreliability of operation. The 
effect of an accumulation of ice, sleet, snow, rain, or dew 
might be serious in connection with flights in high alti- 
tudes or during bad weather. After one of his last year's 
flights at Etampes Mr. Farman is said to have descended 
with an extra load of nearly 200 pounds on this account. 
With ample motor power, great flexibility in weight sus- 
tention is made possible by varying the inclination of the 
planes. In January of this year, Sommer at Douzy car- 
ried six passengers in a large biplane on a cross-country 
flight: and within the week afterward a monoplane oper- 
ated by Le Martin flew for five minutes with the aeronaut 
and seven passengers, at Pau. The total weight lifted 
was about half a ton, and some of the passengers must 
have been rather light. The two-passenger Fort Myer 



Getting Up and Down 



137 



biplane of the Wright brothers is understood to have car- 
ried about this total weight. These records have, how- 






A Monoplane 
(From Aircraft) 

ever, been surpassed since they were noted. Breguet, at 
Douai, in a deeply-arched biplane of new design, carried 



138 Flying Machines Today 

eleven passengers, the total load being 2602 pounds, and 
that of aeronaut and passengers alone 1390 pounds. The 
flight was a short one, at low altitude; but the same aviator 
last year made a long flight with five passengers, and carried 
a load of 1262 pounds at 62 miles per hour. And as if 
in reply to this feat, Sommer carried a live load of 1436 
pounds (13 passengers) for nearly a mile, a day or two 
later, at Mouzon One feels less certain than formerly, 
now, in the snap judgment that the heavier-than-air 
machine will never develop the capacity for heavy loads. 

Miscellaneous 

French aviators are fond of employing a carefully de- 
signed car for the operator and control mechanism. The 
Wright designs practically ignore the car: the aviator sits 
on the forward edge of the lower plane with his legs hang- 
ing over. 

It has been found that auxiliary planes must not be 
too close to the main wings: a gap of a distance about 
50% greater than the width of the widest adjacent plane 
must be maintained if interference with the supporting air 
currents is to be avoided. Main planes are now always 
arched; auxiliary planes, not as universally. The concave 
under surface of supporting wings has its analogy in the 
wing of the bird and had long years since been applied in 
the parachute. 

The car (if used) and all parts of the framework should 
be of "wind splitter" construction, if useless resistance is 



Getting Up and Down 139 

to be avoided. The ribs and braces of the frame are of 
course stronger, weight for weight, in this shape, since a 



Bad 



Top Views of Cars 



Oood 



Sectional Views of Ribs 



narrow deep beam is always relatively stronger than one 
of square or round section. Excessive frictional resist- 
ance is to be avoided by using a smoothly finished fabric 
for the wings, and the method of attaching this fabric 



^Steering Rudder 

Stabilising Planes 





A Double Biplane 




New Position 
for Ailerons 



to the frame should be one that keeps it as flat as pos- 
sible at all joints. 

The sketches give the novel details of some machines 
recently exhibited at the Grand Central Palace in New 



140 Flying Machines Today 

York. The stabilizing planes were invariably found in 
the rear, in all machines exhibited. 

The Things to Look After 

The operator of an aeroplane has to do the work of at 
least two men. No vessel in water would be allowed to 
attain such speeds as are common with air craft, unless 
provided with both pilot and engineer. The aviator is 
his own pilot and his own engineer. He must both man- 
age his propelling machinery and steer. Separate control 
for vertical rudders, elevating rudders and ailerons, for 
starting the engine; the adjustment of the carbureter, the 
spark, and the throttle to get the best results from the 
motor; attention to lubrication and constant watchfulness 
of the water- circulating system: these are a few of the things 
for him to consider; to say nothing of the laying of his 
course and the necessary anticipation of wind and alti- 
tude conditions. 

These things demand great resourcefulness, but — for 
their best control — involve also no small amount of scien- 
tific knowledge. For example, certain adjustments at 
the motor may considerably increase its power, a possibly 
necessary increase under critical conditions: but if such 
adjustments also decrease the motor efficiency there must 
be a nice analysis of the two effects so that extra power 
may not be gained at too great a cost in radius of action. 

The whole matter of flight involves both sportsman's 
and engineer's problems. Wind gusts produce the same 



142 Flying Machines Today 

effects as "turning corners"; or worse — rapidly changing 
the whole balance of the machines and requiring im- 
mediate action at two or three points of control. Both 
ascent and descent are influenced by complicated laws and 
are scarcely rendered safe — under present conditions — 
by the most ample experience. A lateral air current 
bewilders the steering and also demands special prompt- 
ness and skill. To avoid disturbing surface winds, even 
over open country, a minimum flying height of 300 feet 
is considered necessary. This height, furthermore, gives 
more choice in the matter of landing ground than a lower 
elevation. 

When complete and automatic balance shall have been 
attained — as it must be attained — -we may expect to 
see small amateur aeroplanes flying along country roads 
at low elevations — perhaps with a guiding wheel actually 
in contact with the ground. They will cost far less than 
even a small automobile, and the expense for upkeep will 
be infinitely less. The grasshopper will have become a 
water-spider. 



SOME AEROPLANES — SOME ACCOMPLISH- 
MENTS 

The Wright biplane has already been shown (see pages 
31, 37, 121, 122). It was distinguished by the absence 





Orville Wright at Fort Myer, Va., 1908 

of a wheel frame or car and by the wing-warping method of 
stabilizing. Later Wright machines have the spring frame 
and wheels for self-starting. The best known aeroplane 
of this design was built to meet specifications of the United 

143 



Some Aeroplanes — Some Accomplishments 145 

States Signal Corps issued in 1907. It was tried out 
during 1908 at Fort Myer, Va.. while one of the Wright 
brothers was breaking all records in Europe: making 





Wright Motor. Dimensions in millimeters 
(From Petit's Hon' to Build an Aeroplane) 

over a hundred nights in all first carrying a passenger 
and attaining the then highest altitude (360 feet) and 
greatest distance of flight (seventy-seven miles). 

The ownership of the Wrights in the wing-warping 



146 Flying Machines Today 

method of control is still the subject of litigation. The 
French infringers, it is stated, concede priority of appli- 
cation to the Wright firm, but maintain that such pub- 
licity was given the device that it was in general use 
before it was patented. 

The Fort Myer machine had sails of forty feet spread, 
six and one-half feet deep, with front elevating planes 
three by sixteen feet. It made about forty miles per hour 
with two passengers. The apparatus was specified to 
carry a passenger weight of 350 pounds, with fuel for a 
125-mile flight. The main planes were six feet apart. 
The steering rudder (double) was of planes one foot deep 
and nearly six feet high. The four-cylinder-four-cycle, 
water-cooled motor developed twenty-five horse-power at 
1400 revolutions. The two propellers, eight and one-half 
feet in diameter, made 400 revolutions. 

The flight by Mr. Wilbur Wright from the Statue of 
Liberty to the tomb of General Grant, in New York, 1909, 
and the exploits of his brother in the same year, when a new 
altitude record of 1600 feet was made and H.R.H. the 
Crown Prince of Germany was taken up as a passenger, 
are only specimens of the later work done by these pioneers 
in aerial navigation. 

Like the Wrights, the Voisin firm from the beginning 
adhered firmly to the biplane type of machine. The 
sketch gives dimensions of one of the early cellular forms 
built for H. Farman (see illustration, page 147). The 
metal screw makes about a thousand revolutions. The 



Some Aeroplanes — Some Accomplishments 147 



wings are of india rubber sheeting on an ash frame, the 
whole frame and car body being of wood, the latter cov- 
ered with canvas and thirty inches wide by ten feet long. 
The engine weighed 175 pounds. The whole weight of 
this machine was nearly 1200 pounds; that built later for 
Delagrange was brought under a thousand pounds. The 
ratio of weight to main surface in the Farm an aeroplane 
was about i\ to 1. 

A modified cellular biplane also built for Farman had a 
main wing area of 560 square feet, the planes being sev- 









Tit r1^>^ 

fr^^liA/ \ / / 
t^ 1 Motor i Lnrrrir^ — ■— — — ^___ 

1 V J 

1 ^ -^ 


7*- -*&!- J 














~~~~y£iL£*aoe s ' / Steering Rudder 








Eh 


vating 


Rudder 


<~- J. 120'/ M 05 Usual Flying Angle 

\/ ~~~M"^—~~ / 6 t0 8 deg ' 




1 
K 

1 Line of center of weight 
' in ordinary operation 





Voisin-Farman Biplane 

enty-nine inches wide and only fifty-nine inches apart. 
The tail was an open box, seventy-nine inches wide and of 
about ten feet spread. The cellular partitions in this tail 
were pivoted along the vertical front edges so as to serve 
as steering rudders. The elevating rudder was in front. 
The total weight was about the same as that of the first 
machine and the usual speed twenty-eight miles per hour. 
Henry Farman has been flying publicly since 1907. He 



148 Flying Machines Today 

made the first circular flight of one kilometer, and attained 
a speed of about a mile a minute, in the year following. 




The Champagne Grand Prize Won by Henry Farman 
80 Kilometers in 3 hours 

In 1909 he accomplished a trip of nearly 150 miles, remain- 
ing four hours in the air. Farman was probably the first 
man to ascend with two passengers. 



150 Flying Machines Today 

The June Bug, one of the first Curtiss machines, is 
shown below. This was one of the lightest of biplanes, 
having a wing spread of forty-two feet and an area of 
370 square feet. The wings were transversely arched, 
being furthest apart at the center: an arrangement which 
has not been continued. It had a box tail, with a steer- 
ing rudder of about six square feet area, above the tail. 
The horizontal rudder, in front, had a surface of twenty 




The "June Bus" 

square feet. Four triangular ailerons were used for stabil- 
ity. The machine had a landing frame and wheels, made 
about forty miles per hour, and weighed, in operation, 
650 pounds. 

Mr. Curtiss first attained prominence in aviation circles 
by winning the Scientific American cup by his flight at 
the speed of fifty-seven miles per hour, in 1908. In the 
following year he exhibited intricate curved flights at 
Mineola, and circled Governor's Island in New York 



Some Aeroplanes — Some Accomplishments 151 

harbor. In 19 10 he made his famous flight from Albany 
to New York, stopping en route, as prearranged. At 
Atlantic City he flew fifty miles over salt water. A flight 
of seventy miles over Lake Erie was accomplished in Sep- 
tember of the same year, the return trip being made the 
following day. On January 26, 191 1, Curtiss repeatedly 




(Photo by Levick. X.V.) 

Curtiss Biplane 



ascended and descended, with the aid of hydroplanes, in 
San Diego bay, California: perhaps one of the most im- 
portant of recent achievements. It is understood that 
Mr. Curtiss is now attempting to duplicate some of these 
performances under the high -altitude conditions of Great 
Salt Lake. According to press reports, he has been invited 



152 Flying Machines Today 

to give a similar demonstration before the German naval 
authorities at Kiel. 

The aeroscaphe of Ravard was a machine designed to 
move either on water or in air. It was an aeroplane with 




Curtiss' Hydro-Aeroplane at San Diego Getting under Way 
(From the Columbian Magazine) 

pontoons or floaters. The supporting surface aggregated 
400 square feet, and the gross weight was about 1100 
pounds. A fifty horse-power Gnome seven-cylinder motor 
at 1200 revolutions drove two propellers of eight and 
ten and one-half feet diameter respectively: the propel- 



Some Aeroplanes — Some Accomplishments 153 

lers being mounted one behind the other on the same 
shaft. 

Ely's great shore-to-warship flight was made without 
the aid of the pontoons which he carried. Ropes were 
stretched across the landing platform, running over sheaves 
and made fast to heavy sand bags. As a further precau- 




Flyixg over the Water at Fifty Miles per Hour 
Curtiss at San Diego Bay 
(From the Columbian Magazine) 



tion, a canvas barrier was stretched across the forward 
end of the platform. The descent brought the machine 
to the platform at a distance of forty feet from the upper 
end: grappling hooks hanging from the framework of the 
aeroplane then caught the weighted ropes, and the speed 
was checked (within about sixty feet) so gradually that 
"not a wire or bolt of the biplane was injured." 



156 



Flying Machines Today 




Some Aeroplanes — Some Accomplishments 157 




158 Flying Machines Today 

Recent combinations of aeroplane and automobile, 
and aeroplane with motor boat, have been exhibited. 
One of the latter devices is like any monoplane, except 
that the lower part is a water-tight aluminum boat body 
carrying three passengers. It is expected to start of itself 
from the water and to fly at a low height like a flying 
fish at a speed of about seventy-five miles per hour. 
Should anything go wrong, it is capable of floating on 
the water. ; 

In the San Diego Curtiss flights, the machine skimmed 
along the surface of the bay, then rose to a height of a 
hundred feet, moved about two miles through the air in a 
circular course, and finally alighted close to its starting- 
point in the water. Turns were made in water as well as 
in air, a speed of forty miles per hour being attained while 
"skimming." The " hydroplanes " used are rigid flat 
surfaces which utilize the pressure of the water for sus- 
tention, just as the main wings utilize air pressure. On 
account of the great density of water, no great amount of 
surface is required: but it must be so distributed as to 
balance the machine. The use of pontoons makes it pos- 
sible to rest upon the water and to start from rest. A trip 
like Ely's could be made without a landing platform, with 
this type of machine; the aeroplane could either remain 
alongside the war vessel or be hoisted aboard until ready 
to venture away again. 

There are various other biplanes attracting public atten- 
tion in this country. In France the tendency is all toward 



Some Aeroplanes — Some Accomplishments 159 



the monoplane form, and many of the u records" have, dur- 
ing the past couple of years, passed from the former to 




Santos-Ddmont's : Demoiselle 1 



the latter type of machine. The monoplane is simpler 
and usually cheaper. The biplane may be designed for 



i6o 



Flying Machines Today 



greater economy in weight and power. Farman has 
lately experimented with the monoplane type of machine: 
the large number of French designs in this class discourages 
any attempt at complete description. 

The smallest of aeroplanes is the Santos-Dumont Dem- 
oiselle. The original machine is said to have supported 
260 pounds on 100 square feet of area, making a speed of 
sixty miles per hour. Its proprietor was the first aviator 




Bleriot Monoplane 

in Europe of the heavier- than-air class. After having 
done pioneer work with dirigible balloons, he won the 
Deutsch prize for a hundred meter aeroplane flight (the 
first outside of the United States) in 1906; the speed being 
twenty-three miles per hour. His first flight, of 400 feet, 
in a monoplane was made in 1907. 

The master of the monoplane has been Louis Bleriot. 
Starting in 1907 with short flights in a Langley type of 



Some Aeroplanes — Some Accomplishments 161 

machine, he made his celebrated cross-country run, and 
the first circling nights ever achieved in a monoplane, the 




Latham's Fall into the Channel 

following year. On July 25, 1909, he crossed the British 
Channel, thirty- two miles, in thirty-seven minutes. 
The Channel crossing has become a favorite feat. Mr. 



1 62 Flying Machines Today 

Latham, only two days after Bleriot, all but completed 
it in his Antoinette monoplane. De Lesseps, in a 
Bleriot machine, was more fortunate. Sopwith, last 
year, won the de Forest prize of $20,000 by a flight of 
174 miles from England into Belgium. The ill-fated 
Rolls made the round trip between England and France. 
Grace, contesting for the same prize, reached Belgium, 
was driven back to Calais, started on the return voyage, 
and vanished — all save some few doubtful relics lately 
found. Moisant reached London from Paris — the first 
trip on record between these cities without change of 
conveyance: and one which has just been duplicated by 
Pierre Prier, who, on April 12, made the London to Paris 
journey, 290 miles, in 236 minutes, without a stop. This 
does not, however, make the record for a continuous flight : 
which was attained by Tabuteaw, who at Buc, on Dec. 30, 
1 910, flew around the aerodrome for 465 minutes at the 
speed of 48^ miles per hour. 

Other famous crossings include those of the Irish Sea, 
52 miles, by Loraine; Long Island Sound, 25 miles, by 
Harmon; and Lake Geneva, 40 miles, by Defaux. 

It was just about a century ago that Cayley first de- 
scribed a soaring machine, heavier than air, of a form re- 
markably similar to that of the modern aeroplane. Aside 
from Henson's unsuccessful attempt to build such a ma- 
chine, in 1842, and Wenham's first gliding experiments 
with a triplane in 1857, soaring flight made no real progress 
until Langley's experiments. That investigator, with 



Some Aeroplanes — Some Accomplishments 163 




164 Flying Machines Today 

Maxim and others, ascertained those laws of aerial sus- 
tention the application of which led to success in 1903. 

The eight years since have held the crowded hours of 
aviation. Before this book is printed, it may be rendered 
obsolete by new developments. The exploits of Paulhan, 
of R. E. Pelterie since 1907, Bell's work with his tetrahe- 
dral kites — all have been either stimulating or directly 
fruitful. Delagrange began to break speed records in 1908. 




The Maxim Aeroplane 



A year later he attained a speed of fifty miles. The first 
woman to enjoy an aeroplane voyage was Mme. Dela- 
grange, in Turin, in 1908. 

The first flight in England by an English-built machine 
was made in January, 1909. That year, Count de Lam- 
bert flew over Paris, and in 1910 Grahame-White ciicled 
his machine over the city of Boston. The year 19 10 sur- 



1 66 Flying Machines Today 

passed all its predecessors in increasing the range and 
control of aeroplanes; over 1500 ascents were made by 
Wright machines alone; but 191 1 promises to show even 
greater results. Three men made cross-country nights 
from Belmont Park to the Statue of Liberty and back, 




Robart Monoplane. 



in New York;* at least five men attained altitudes exceed- 
ing 9,000 feet. Hamilton made the run from New York 
to Philadelphia and return, in June. The unfortunate 
Chavez all but abolished the fames of Hannibal and Napo- 

* The contestants for the Ryan prize of $10,000 were Moisant, Count 
de Lesseps, and Grahame-White. Owing to bad weather, there was no 
general participation in the preliminary qualifying events, and some ques- 
tion exists as to whether such qualification was not tacitly waived; par- 
ticularly in view of the fact that the prize was awarded to the technically 
unqualified competitor, Mr. Moisant, who made the fastest time. This 
award was challenged by Mr. Grahame-White, and upon review by the 
International Aeronautic Federation the prize was given to de Lesseps, the 
slowest of the contestants, Grahame-White being disqualified for having 
fouled a pylon at the start. This gentleman has again appealed the case, 
and a final decision cannot be expected before the meeting of the Federa- 
tion in October, 191 1. 



Some Aeroplanes — Some Accomplishments 167 

leon by crossing the icy barrier of the Alps, from Switzer- 
land to Italy — in forty minutes ! 

Tabuteau, almost on New Year's eve, broke all distance 
records by a flight of 363 miles in less than eight hours; 
while Barrier at Memphis probably reached a speed of 
eighty-eight miles per hour (timing unofficial). With the 
new year came reports of inconceivable speeds by a ma- 
chine skidding along the ice of Lake Erie; the successful 




Vina Monoplane. 



receipt by Willard and McCurdy of wireless messages 
from the earth to their aeroplanes; and the proposal by 
the United States Signal Corps for the use of flying 
machines for carrying Alaskan mails. 

McCurdy all but succeeded in his attempt to fly from 
Key West to Havana, surpassing previous records by 
remaining aloft above salt water while traveling eighty 
miles. Lieutenant Bague, in March, started from Antibes, 
near Xice, for Corsica. After a 124-mile flight, breaking all 
records for sea journeys by air, he reached the islet of Gor- 



1 68 Flying Machines Today 

gona, near Leghorn, Italy, landing on bad ground and badly 
damaging his machine. The time of flight was 5 J hours. 
Bellinger completed the 500-mile "accommodation train" 
flight from Vincennes to Pau; Vedrine, on April 12, by 
making the same journey in 415 minutes of actual flying 
time, won the Beam prize of $4000; Say attained a speed 
of 74 miles per hour in circular flights at Issy-les-Mouli- 
neaux. Aeroplane flights have been made in Japan, India, 
Peru, and China. 

One of the most spectacular of recent achievements is 
that of Renaux, competing for the Michelin Grand Prize. 
A purse of $20,000 was offered in 1909 by M. Michelin, the 
French tire manufacturer, for the first successful flight 
from Paris to Clermont-Ferrand — 260 miles — in less 
than six hours. The prize was to stand for ten years. It 
was prescribed that the aviator must, at the end of the 
journey, circle the tower of the Cathedral and alight on 
the summit of the Puy de Dome — elevation 4500 feet — 
on a landing place measuring only 40 by 100 yards, sur- 
rounded by broken and rugged ground and usually obscured 
by fog. 

The flight was attempted last year by Weymann, who 
fell short of the goal by only a few miles. Leon Morane 
met with a serious accident, a little later, while attempting 
the trip with his brother as a passenger. Renaux completed 
the journey with ease in his Farman biplane, carrying a 
passenger, his time being 308 minutes. 

This Michelin Grand Prize is not to be confused with the 



Some Aeroplanes — Some Accomplishments 169 

Michelin Trophy of $4000 offered yearly for the longest 
flight in a closed circuit. 

Speeds have increased 50% during the past year; even 
with passengers, machines have moved more than a mile 
a minute: average motor capacities have been doubled 
or tripled. The French men and machines hold the rec- 
ords for speed, duration, distance, and (perhaps) altitude. 
The highest altitude claimed is probably that attained by 
Garros at Mexico City, early this year — 12,052 feet above 
sea level. The world's speed record for a two-man flight 
appears to be that of Foulois and Parmalee, made at Laredo, 
Texas, March 3, 191 1 : 106 miles, cross-country, in 127 min- 
utes. Three-fourths of all flights made up to this time have 
been made in France — a fair proportion, however, in 
American machines. 

NOTE 

The rapidity with which history is made in aeronautics is forci- 
bly suggested by the revision of text made necessary by recent 
news. The new Deutschland has met the fate of its predecessors; 
the Paris-Rome-Turin flight is at this moment under way; and 
Lieutenant Bayne, attempting once more his France-to-Corsica 
flight, has — for the time being at least — disappeared. 



THE POSSIBILITIES IN AVIATION 

Men now fly and will probably keep on flying; but avia- 
tion is still too hazardous to become the popular sport of 
the average man. The overwhelmingly important prob- 
lem with the aeroplane is that of stability. These machines 
must have a better lateral balance when turning corners 
or when subjected to wind gusts: and the balance must 
be automatically, not manually, produced. 




Blanc Monoplane 

Other necessary improvements are of minor urgency and 
in some cases will be easy to accomplish. Better mechan- 
ical construction, especially in the details of attachments, 
needs only persistence and common sense. Structural 
strength will be increased; the wide spread of wing pre- 
sents difficulties here, which may be solved either by 

170 



The Possibilities in Aviation 



171 



increasing the number of superimposed surfaces, as in tri- 
planes, or in some other manner. Greater carrying capac- 




Melvin Vaniman Triplane 



ity — two men instead of one — may be insisted upon : 
and this leads to the difficult question of motor weights. 
The revolving air-cooled motor may offer further possibil- 




Jean de Crawhez Triplane 

ities : the two-cycle idea will help if a short radius of action 
is permissible: but a weight of less than two pounds to 



i7 2 Flying Machines Today 

the horse-power seems to imply, almost essentially, a lack 
of ruggedness and surety of operation. A promising field 



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for investigation is in the direction of increasing propeller 
efficiencies. If such an increase can be effected, the whole 
of the power difficulty will be greatly simplified. 



The Possibilities in Aviation 173 

This same motor question controls the proposal for 
increased speed. The use of a reserve motor would again 
increase weights; though not necessarily in proportion to 
the aggregate engine capacity. Perhaps something may 
be accomplished with a gasoline turbine, when one is 
developed. In any case, no sudden increase in speeds 
seems to be probable; any further lightening of motors 
must be undertaken with deliberation and science. If 
much higher maximum speeds are attained, there will be 
an opportunity to vary the speed to suit the requirements. 
Then clutches, gears, brakes, and speed-changing devices 
of various sorts will become necessary, and the problem of 
weights of journal bearings — already no small matter — 
will be made still more serious. And with variable speed 
must probably come variable sail area — in preference to 
tilting — so that the fabric must be reefed on its frame. 
Certainly two men, it would seem, will be needed! 

Better methods for starting are required. The hydro- 
plane idea promises much in this respect. With a better 
understanding and control of the conditions associated 
with successful and safe descent — perhaps with improved 
appliances therefor — the problem of ascent will also be 
partly solved. If such result can be achieved, these 
measures of control must be made automatic. 

The building of complete aeroplanes to standard designs 
would be extremely profitable at present prices, which 
range from S2500 to S5000. Perhaps the most profitable 
part would be in the building of the motor. The framing 



174 Flying Machines Today 

and fabric of an ordinary monoplane could easily be con- 
structed at a cost below $300. The propeller may cost 
$50 more. The expense for wires, ropes, etc., is trifling; 
and unless special scientific instruments and accessories 
are required, all of the rest of the value lies in the motor 
and its accessories. Within reasonable limits, present costs 
of motors vary about with the horse-power. The amateur 
designer must therefore be careful to keep down weight and 
power unless he proposes to spend money quite freely. 

The Case of the Dirigible 

Not very much is being heard of performances of diri- 
gible balloons just at present. They have shown them- 
selves to be lacking in stanchness and effectiveness under 
reasonable variations of weather. We must have fabrics 
that are stronger for their weight and more impervious. 
Envelopes must be so built structurally as to resist deforma- 
tion at high speeds, without having any greatly increased' 
weight. A cheap way of preparing pure hydrogen gas 
is to be desired. 

Most important of all, the balloon must have a higher 
speed, to make it truly dirigible. This, with sufficient 
steering power, will protect it against the destructive 
accidents that have terminated so many balloon careers. 
Here again arises the whole question of power in relation 
to motor weight, though not as formidably as is the case 
with the aeroplane. The required higher speeds are pos- 
sible now, at the cost merely of careful structural design, 



The Possibilities in Aviation 175 

reduced radius of action, and reduced passenger carrying 
capacity. 

Better altitude control will be attained with better fab- 
rics and the use of plane fin surfaces at high speeds. The 
employment of a vertically-acting propeller as a somewhat 
wasteful but perhaps finally necessary measure of safety 
may also be regarded as probable. 




Giraudon's Wheel Aeroplane 

The Orthopter 

The avi plane, ornithoptere or orthopter is a flying machine 
with bird-like flapping wings, which has received occa- 
sional attention from time to time, as the result of a too 
blind adherence to Nature's analogies. Every mechanical 
principle is in favor of the screw as compared with any 
reciprocating method of propulsion. There have been 
few actual examples of this type: a model was exhibited 
at the Grand Central Palace in New York in January of 
this year. 



176 Flying Machines Today 

The mechanism of an orthopter would be relatively 
complex, and the flapping wings would have to "feather" 
on their return stroke. The flapping speed would have to 
be very high or the surface area very great. This last 
requirement would lead to structural difficulties. Pro- 
pulsion would not be uniform, unless additional compli- 
cations were introduced. The machine would be the most 
difficult of any type to balance. The motion of a bird's 
wing is extremely complicated in its details — one that it 
would be as difficult to imitate in a mechanical device as 
it would be for us to obtain the structural strength of an 
eagle's wing in fabric and metal, with anything like the 
same extent of surface and limit of weight. According to 
Pettigrew, the efficiency of bird and insect flight depends 
largely upon the elasticity of the wing. Chatley gives the 
ratio of area to weight as varying from fifty (gnat) to 
one-half (Australian crane) square feet per pound. The 
usual ratio in aeroplanes is from one-third to one-half. 

About the only advantages perceptible with the orthop- 
ter type of machine would be, first, the ability "to start 
from rest without a preliminary surface glide"; and sec- 
ond, more independence of irregularity in air currents, 
since the propulsive force is exerted over a greater extent 
than is that of a screw propeller. 

The Helicopter 

The gyroplane or helicopter was the type of flying machine 
regarded by Lord Kelvin as alone likely to survive. It 



178 Flying Machines Today 

lifts itself by screw propellers acting vertically. This 
form was 'suggested in 1852. When only a single screw 
was used, the whole machine rotated about its vertical 
axis. It was attempted to offset this by the use of vertical 
fin-planes: but these led to instability in the presence of 
irregular air currents. One early form had two oppositely- 
pitched screws driven by a complete steam engine and 
boiler plant. One of the Cornu helicopters had adjustable 
inclined planes under the two large vertically propelling 
screws. The air which slipped past the screws imposed 
a pressure on the inclined planes which was utilized to 
produce horizontal movement in any desired direction — 
if the wind was not too adverse. A gasoline engine was 
carried in a sort of well between the screws. 

The helicopter may be regarded as the limiting type of 
aeroplane, the sail area being reduced nearly to zero; the 
wings becoming mere fins, the smaller the better. It 
therefore requires maximum motor power and is particu- 
larly dependent upon the development of an excessively 
light motor. It is launched and descends under perfect 
control, without regard to horizontal velocity. It has 
very little exposed surface and is therefore both easy to 
steer and independent of wind conditions. By properly 
arranging the screws it can be amply balanced: but it must 
have a particularly stout and strong frame. 

The development of this machine hinges largely on the 
propeller. It is not only necessary to develop power 
(which means force multiplied by velocity) but actual 



The Possibilities in Aviation 179 

propulsive vertical force: and this must exceed or at least 
equal the whole weight of the machine. From ten to 
forty pounds of lifting force per horse-power have been 
actually attained: and with motors weighing less than five 
pounds there is evidently some margin. The propellers 
are of special design, usually with very large blades. Four 
are commonly used: one, so to speak, at each "corner" 
of the machine. The helicopter is absolutely dependent 
upon its motors. It cannot descend safely if the power 
fails. If it is to do anything but ascend and descend it 
must have additional propulsive machinery for producing 
horizontal movement. 

Composite Types 

The aeroplane is thus particularly weak as to stability, 
launching, and descending: but it is economical in power 
because it uses the air to hold itself up. The dirigible 
balloon is lacking in power and speed, but can ascend and 
descend safely, even if only by wasteful methods; and it 
can carry heavy weights, which are impossible with the 
structurally fragile aeroplane. The helicopter is waste- 
ful in power, but is stable and sure in ascending and 
descending, providing only that the motor power does not 
fail. 

Why, then, not combine the types? An aeroplane- 
dirigible would be open to only one objection: on the 
ground of stability. The dirigible-helicopter would have 
as its only disadvantage a certain wastefulness of power, 



180 Flying Machines Today 

while the aeroplane-helicopter would seem to have no 
drawback whatever. 

All three combinations have been, or are being, tried. 
An Italian engineer officer has designed a balloon-aero- 
plane. The balloon is greatly flattened, or lens-shaped, 
and floats on its side, presenting its edge to the horizon — 
if inclination be disregarded. With some inclination, the 
machine acts like an aeroplane and is partially self-sustain- 
ing at any reasonable velocity. 

The use of a vertically-acting screw on a dirigible com- 
bines the features of that type and the helicopter. This 
arrangement has also been the subject of design (as in 
Captain Miller's flexible balloon) if not of construction. 
The combination of helicopter and aeroplane seems espe- 
cially promising : the vertical propellers being employed for 
starting and descending, as an emergency safety feature 
and perhaps for aid in stabilizing. The fact that composite 
types of flying machine have been suggested is perhaps, 
however, an indication that the ultimate type has not 
yet been established. 

What is Promised 

The flying machine will probably become the vehicle 
of the explorer. If Stanley had been able to use a small 
high-powered dirigible in the search for Livingstone, the 
journey would have been one of hours as compared with 
months, the food and general comfort of the party would 
have been equal in quality to those attainable at home, 



The Possibilities in Aviation 



181 



and the expense in money and in human life would 
have been relatively trifling. 

Most readers will remember the fate of Andree, and the 
projected polar expeditions of Wellman in 1907 and 1909. 
Misfortune accompanied both attempts; but one has only 
to read Peary's story of the dogged tramp over the Green- 










sssf£a»as*MMre 



irn^tmh 






Wellman's America 

(From Wellman's Aerial Age) 

land ice blink to realize that danger and misfortune in 
no less degree have accompanied other plans of Arctic 
pioneering. With proper design and the right men, it 
does not seem unreasonable to expect that a hundred 
flying machines may soar above Earth's invisible axial 
points during the next dozen years.* 

*The high wind velocities of the southern circumpolar regions may be 
an insurmountable obstacle in the Antarctic. Yet Mawson expects to 
take with him a 2-passenger monoplane having a 180-mile radius of action 
on the expedition proposed for this year. 



1 82 Flying Machines Today 

The report of Count Zeppelin's Spitzbergen expedi- 
tion of last year has just been made public. This 
was undertaken to ascertain the adaptability of flying 
machines for Arctic navigation. Besides speed and ra- 
dius of action, the conclusive factors include that of 
freedom from such breakdowns as cannot be made good 
on the road. 

For exploration in other regions, the balloon or the aero- 
plane is sure to be employed. Rapidity of progress with- 
out fatigue or danger will replace the floundering through 
swamps, shivering with ague, and bickering with hostile 
natives now associated with tropical and other expeditions. 
The stereoscopic camera with its scientific adjuncts will 
permit of almost automatic map-making, more compre- 
hensive and accurate than any now attempted in other 
than the most settled sections. It is not too much to 
expect that arrangements will be perfected for conducting 
complete topographical surveys without more than occa- 
sional descents. If extremely high altitudes must be 
attained — over a mile — the machines will be of special 
design; but as far as can now be anticipated, there will 
be no insurmountable difficulties. The virgin peaks of 
Ruwenzori and the Himalayas may become easily access- 
ible — even to women and children if they desire it. We 
may obtain direct evidence as to the contested ascent of 
Mt. McKinley. A report has been current that a Bleriot 
monoplane has been purchased for use in the inspection 
of construction work for an oil pipe line across the Persian 



The Possibilities in Aviation 183 

desert; the aeroplane being regarded as "more expedi- 
tious and effectual" than an automobile. 

The flying machine is the only land vehicle which 
requires no "permanent way." Trains must have rails, 
bicycles and automobiles must have good roads. Even 
the pedestrian gets along better on a path. The ships of 
the air and the sea demand no improvement of the fluids 
in which they float. To carry mails, parcels, persons, and 
even light freight — these applications, if made commer- 
cially practicable tomorrow,* would surprise no one; their 
possibility has already been amply demonstrated. With 
the dirigible as the transatlantic liner and the aeroplane 
as the naphtha launch of the air, the whole range of appli- 
cations is commanded. Hangars and landing stages — 
the latter perhaos on the roofs of buildings, revolutioniz- 
ing our domestic architecture — may spring up as rapidly 
as garages have done. And the aeroplane is potentially 
(with the exception of the motorcycle) the cheapest of 
self-propelled vehicles. 

Governments have already considered the possibilities 
of aerial smuggling. Perhaps our custom-house officers 
will soon have to watch a fence instead of a line: to barri- 
cade in two dimensions instead of one. They will need 
to be provided with United States Revenue aeroplanes. 
But how are aerial frontiers to be marked? And does a 



* It seems that tomorrow has come; for an aeroplane is being regu- 
larly used (according to a reported interview with Dr. Alexander Graham 
Bell) for carrying mails in India. 



184 Flying Machines Today 

nation own the air above it, or is this, like the high seas, 
" by natural right, common to all" ? Can a flying-machine 
blockade-runner above the three-mile height claim extra- 
territoriality? 

The flying machine is no longer the delusion of the 
"crank," because it has developed a great industry. A 
now antiquated statement put the capitalization of aero- 
plane manufactories in France at a million dollars, and the 
development expenditure to date at six millions. There 
are dozens of builders, in New York City alone, of mono- 
planes, biplanes, gliders, and models. A permanent exhi- 
bition of air craft is just being inaugurated. We have now 
even an aeronautic " trust," since the million-dollar cap- 
italization of the Maxim, Bleriot, Grahame-White firm. 

According to the New York Sun, over $500,000 has been 
subscribed for aviation prizes in 191 1. The most valuable 
prizes are for new records in cross-country flights. The 
Paris Journal has offered $70,000 for the best speed in a 
circling race from Paris to Berlin, Brussels, London, and 
back to Paris — 1500 miles. Supplementary prizes from 
other sources have increased the total stake in this race to 
$100,000. A purse of $50,000 is offered by the London 
Daily Mail for the " Circuit of Britain" race, from London 
up the east coast to Edinburgh, across to Glasgow, and 
home by way of the west coast, Exeter, and the Isle of 
Wight; a thousand miles, to be completed in two weeks, 
beginning July 22, with descents only at predetermined 
points. This contest will be open (at an entrance fee of 



The Possibilities in Aviation 185 

S500) to any licensee of the International Federation. A 
German circuit, from Berlin to Bremen, Magdeburg, Diissel- 
dorf, Aix-la-Chapelle, Dresden, and back to the starting 
point, is proposed by the Zeitung am Mitt a g of Berlin, a 
prize of 825,000 having been offered. In this country, a 
comparatively small prize has been established for a run 
from San Francisco to New York, via Chicago. Besides a 
meet at Bridgeport, May 18-20, together with those to be 
held by several of the colleges and the ones at Bennings 
and Chicago, there will be, it is still hoped, a national 
tournament at Belmont Park at the end of the same month. 
Here probably a dozen aviators will contest in qualification 
for the international meet in England, to which three 
American representatives should be sent as competitors 
for the championship trophy now held by Mr. Grahame- 
White. It is anticipated that the chances in the inter- 
national races favor the French aviators, some of whom — 
in particular, Leblanc — have been making sensational 
records at Pau. Flights between aviation fields in different 
cities are the leading feature in the American program for 
the year. A trip is proposed from Washington to Belmont 
Park, via Atlantic City, the Xew Jersey coast, and lower 
Xew York bay. The distance is 250 miles and the time 
will probably be less than that of the best passenger trains 
between Washington and Xew York. If held, this race 
will probably take place late in May. It is wisely concluded 
that the advancement of aviation depends upon cross- 
country runs under good control and at reasonable speeds 



1 86 Flying Machines Today 

and heights rather than upon exhibition flights in enclo- 
sures. It is to be hoped that commercial interests will not 
be sufficiently powerful to hinder this development. 

We shall of course have the usual international champion- 
ship balloon race, preceded by elimination contests. From 
present indications Omaha is likely to be chosen as the 
point of departure. 

The need for scientific study of aerial problems is 
recognized. The sum of $350,000 jhas been offered the 
University of Paris to found an aeronautic institute. In 
Germany, the university at Gottingen has for years main- 
tained an aerodynamic laboratory. Lord Rayleigh, in 
England, is at the head of a committee of ten eminent 
scientists and engineers which has, under the authority 
of Parliament, prepared a program of necessary theoret- 
ical and experimental investigations in aerostatics and aero- 
dynamics. Our American colleges have organized student 
aviation societies and in some of them systematic instruc- 
tion is given in the principles underlying the art. A per- 
manent aeronautic laboratory, to be located at Washington, 
D.C., is being promoted. 

Aviation as a sport is under the control of the Interna- 
tional Aeronautic Federation, having its headquarters at 
Paris. Bodies like the Royal Aero Club of England and 
the Aero Club of America are subsidiaries to the Federation. 
In addition, we have in this country other clubs, like 
the Aeronautic Society, the United States Aeronautical 
Reserve, etc. The National Council of the Aero Clubs of 



The Possibilities in Aviation 187 

America is a sort of supreme court for all of these, having 
control of meets and contests; but it has no affiliation 
with the International body, which is represented here by 
the Aero Club of America. The Canadian Auto and Aero 
Club supervises aviation in the Dominion 

Aviation has developed new legal problems: problems 
of liability for accidents to others; the matter of super- 
vision of airship operators. Bills to license and regulate 
air craft have been introduced in at least two state legis- 
latures. 

Schools for instruction in frying as an art or sport are 
being promoted. It is understood that the Wright firm 
is prepared to organize classes of about a dozen men, sup- 
plying an aeroplane for their instruction. Each man pays 
a small fee, which is remitted should he afterward pur- 
chase a machine. Mr. Grahame- White, at Pau, in the 
south of France, conducts a school of aviation, and the 
arrangements are now being duplicated in England. In- 
struction is given on Bleriot monoplanes and Farman 
biplanes, at a cost of a hundred guineas for either. The 
pupil is coached until he can make a three-mile flight; 
meanwhile, he is held partially responsible for damage 
and is required to take out a ''third-party" insurance 
policy. 

There is no lack of aeronautic literature. Major Squier's 
paper in the Transactions of the American Society of 
Mechanical Engineers, 1908, gave an eighteen-page list 
of books and magazine articles of fair completeness up 



1 88 Flying Machines Today 

to its date; Professor Chatley's book, Aeroplanes, 191 1, 
discusses some recent publications; the Brooklyn Public 
Library in New York issued in 19 10 (misdated 1909) a 
manual of fourteen pages critically referring to the then 
available literature, and itself containing a list of some 
dozen bibliographies. 



AERIAL WARFARE 

The use of air craft as military auxiliaries is not new. 
As early as 1812 the Russians, before retreating from Mos- 
cow, attempted to drop bombs from balloons : an attempt 
carried to success by Austrian engineers in 1849. Both 




(Photo by Paul Thompson) 



contestants in our own War of Secession employed captive 
and drifting balloons. President Lincoln organized a 
regular aeronautic auxiliary staff in which one Lowe held 
the official rank of chief aeronaut. This same gentleman 
(who had accomplished a reconnaissance of 350 miles in 
eight hours in a 25,000 cubic foot drifting balloon) was 



190 



Flying Machines Today 



subjected to adverse criticism on account of a weakness 
for making ascents while wearing the formal "Prince 
Albert" coat and silk hat! A portable gas-generating 
plant was employed by the Union army. We are told 
that General Stoneman, in 1862, directed artillery fire 
from a balloon, which was repeatedly fired at by the 
enemy, but not once hit. The Confederates were less 
amply equipped. Their balloon was a patchwork of silk 
skirts contributed (one doubts not, with patriotic alacrity) 
by the daughters of the Confederacy. 

It is not forgotten that communication between be- 
sieged Paris and the external world was kept up for some 
months during 1870-71 by balloons exclusively. Mail 
was carried on a truly commercial scale: pet animals 
and — the anticlimax is unintended — 164 persons, includ- 
ing M. Gambetta, escaped in some sixty-five flights. 
Balloons were frequently employed in the Franco-Prussian 
contest; and they were seldom put hors de combat by the 
enemy. 

During our war with Spain, aerial craft were employed 
in at least one instance, namely, at San Juan, Porto Rico, 
for reconnoitering entrenchments. Frequent ascents were 
made from Ladysmith, during the Boer war. The balloons 
were often fired at, but never badly damaged. Cronje's 
army was on one occasion located by the aid of a British 
scout-balloon. Artillery fire was frequently directed from 
aerial observations. Both sides employed balloons in 
the epic conflict between Russia and Japan. 



Aerial Warfare 191 

A declaration introduced at the second international 
peace conference at the Hague proposed to prohibit, for 
a limited period, the discharge of projectiles or explosives 
from flying machines of any sort. The United States was 
the only first-class power which endorsed the declaration. 
It does not appear likely, therefore, that international law 
will discountenance the employment of aerial craft in 
international disputes. The building of airships goes on 
with increasing eagerness. Last year the Italian chamber 
appropriated $5,000,000 for the construction and mainte- 
nance of flying machines. 

A press report dated February 4 stated that a German 
aeronaut had been spending some weeks at Panama, 
studying the air currents of the Canal Zone. No flying 
machine may in Germany approach more closely than 
within six miles of a fort, unless specially licensed. At 
the Krupp works in Essen there are being tested two 
new guns for shooting at aeroplanes and dirigibles. One 
is mounted on an armored motor truck. The other is a 
swivel-mounted gun on a flat-topped four-wheeled carriage. 

The United States battleship Connecticut cost $9,000,000. 
It displaces 18,000 tons, uses 17,000 horse-power and 
1000 men, and makes twenty miles an hour. An aero- 
plane of unusual size with nearly three times this speed, 
employing from one 1o three men with an engine of 100 
horse-power, would weigh one ton and might cost $5000. 
A Dreadnought costs $16,000,000, complete, and may last 
— it is difficult to say, but few claim more than ten 



192 Flying Machines Today 

years. It depreciates, perhaps, at the rate of $2,000,000 a 
year. Aeroplanes built to standard designs in large quan- 
tities would cost certainly not over $1000 each. The 
ratio of cost is 16,000 to 1. Would the largest Dread- 
nought, exposed unaided to the attack of 16,000 flying 
machines, be in an entirely enviable situation? 

An aeroplane is a fragile and costly thing to hazard at 
one blow: but not more fragile or costly than a Whitehead 
torpedo. The aeroplane soldier takes tremendous risks; 
but perhaps not greater risks than those taken by the crew 
of a submarine. There is never any lack of daring men 
when daring is the thing needed. 

All experience goes to show that an object in the air is 
hard to hit. The flying machine is safer from attack 
where it works than it is on the ground. The aim neces- 
sary to impart a crippling blow to an aeroplane must be 
one of unprecedented accuracy. The dirigible balloon 
gives a larger mark, but could not be immediately crippled 
by almost any projectile. It could take a good pounding 
and still get away. Interesting speculations might be made 
as to the outcome of an aerial battle between the two types 
of craft. The aeroplane might have a sharp cutting 
beak with which to ram its more cumbersome adversary, 
but this would involve some risk to its own stability: and 
the balloon could easily escape by a quick ascent. It has 
been suggested that each dirigible would need an aero- 
plane escort force for its defense against ramming. Any 
collision between two opposing heavier- than-air machines 



Aerial Warfare 



!93 



could not, it would seem, be other than disastrous: but 
perhaps the dirigible could rescue the wrecks. Possibly 
gas-inflated life buoys might be attached to the individual 
combatants. In the French manceuvers, a small aero- 
plane circled the dirigible with ease, flying not only around 
it, but in vertical circles over and under it. 




7.5 Centimeter German Automatic Gun for Attacking Airships 
(From Brewer's Art of Aviation) 



The French war office has exploited both types of 
machine. In Germany, the dirigible has until recently 
received nearly all the attention of strategists: but the 
results of a recent aerial war game have apparently sug- 
gested a change in policy, and the Germans are now, 



194 Flying Machines Today 

without neglecting the balloon, actively developing its 
heavier-than-air competitor. England seems to be muddled 
as to its aerial policy, while the United States has been 
waiting and for the most part doing nothing. Now, how- 
ever, the mobilizations in Texas have been associated with 
a considerable amount of aeroplane enthusiasm. A half- 
dozen machines, it is expected, will soon be housed in the 
aerodrome at San Antonio. Experiments are anticipated 
in the carrying of light ammunition and emergency supplies, 
and one of the promised manceuvers is to be the locating 
of concealed bodies of troops by air scouts. Thirty army 
officers are to be detailed for aeroplane service this year; 
five training schools are to be established. 

If flying machines are relatively unsusceptible to attack, 
there is also some question as to their effectiveness in 
attack. Rifles have been discharged from moving bal- 
loons with some degree of accuracy in aim; but long-range 
marksmanship with any but hand weapons involves the 
mastery of several difficult factors additional to those 
present in gunnery at sea. The recoil of guns might 
endanger stability; and it is difficult to estimate the 
possible effects of a powerful concussion, with its resulting 
surges of air, in the immediate vicinity of a delicately 
balanced aerial vessel. 

But aside from purely combative functions, air craft 
may be superlatively useful as messengers. To send 
despatches rapidly and without interference, or to carry 
a general ioo miles in as many minutes — these accom- 



Aerial Warfare 195 

plishments would render impossible the romance of a 
"Sheridan's Ride," but might have a romance of their 
own. With the new sense added to human equipment by 
wireless communication, the results of observations may be 
signaled to friends over miles of distance without inter- 
vening permanent connections of however fragile a nature. 
Flying machines would seem to be the safest of scouts. 
They could pass over the enemy's country with as little 
direct danger — perhaps as unobserved — as a spy in 
disguise; yet their occupants would scarcely be subjected 
to the penalty accompanying discovery of a spy. They 
could easily study the movements of an opposing armed 
force: a study now frequently associated with great loss 
of life and hampering of effective handling of troops. 
They could watch for hostile fleets with relatively high 
effectiveness (under usual conditions), commanding dis- 
tant approaches to a long coast line at slight cost. From 
their elevated position, they could most readily detect 
hostile submarines threatening their own naval fleet. 
Maximum effective reconnaissance in minimum time would 
be their chief characteristic: in fact, the high speeds might 
actually constitute an objection, if they interfered with 
thorough observation. But if air craft had been' avail- 
able at Santiago in 1898, Lieutenant Blue's expedition 
would have been unnecessary, and there would have been 
for no moment any doubt that Admiral Cervera's fleet 
was actually bottled up behind the Monro. No besieged 
fortress need any longer be deprived of communication 



196 Flying Machines Today 

with — or even some medical or other supplies from — 
its friends. Suppose that Napoleon had been provided 
with a flying machine at Elba — or even at St. Helena! 

The applications to rapid surveying of unknown ground 
that have been suggested as possible in civil life would 
be equally possible in time of war. Even if the scene of 
conflict were in an unmapped portion of the enemy's terri- 
tory, the map could be quickly made, the location of tem- 
porary defenses and entrenchments ascertained, and the 
advantage of superior knowledge of the ground completely 
overcome prior to an engagement. The searchlight and 
the compass for true navigation on long flights over un- 
known country would be the indispensable aids in such 
applications. 

During the current mobilization of the United States 
Army at Texas, a despatch was carried 21 miles on a map- 
and-compass flight, the round trip occupying less than two 
hours, and being made without incident. The machine 
flew at a height of 1500 feet and was sighted several miles 
off. 

A dirigible balloon, it has been suggested, is compara- 
tively safe while moving in the air, but is subjected to 
severe strains when anchored to the ground, if exposed. 
It must have either safe harbors of refuge or actual shelter 
buildings — dry docks, so to speak. In an enemy's coun- 
try a ravine or even a deep railway cut might answer in an 
emergency: but the greatest reliance would have to be 
placed on quick return trips from a suitable base. The 



Aerial Warfare 197 

balloon would be, perhaps, a more effective weapon in 
defense than in attack. Major Squier regards a flying 
height of one mile as giving reasonable security against 
hostile projectiles in the daytime. A lower elevation 



V 


\ 


l\\ 





Geeman Gun for 'Shooting at 

Aeroplanes 

(From Brewer's Art of Aviation) 

would be sufficient at night. Given a suitable telepho to- 
graphic apparatus, all necessary observations could easily 
be made from this altitude. Even in the enemy's territory, 
descent to the earth might be possible at night under rea- 



198 Flying Machines Today 

sonably favorable conditions. Two sizes of balloon would 
seem to be indicated: the scouting work described would 
be done by a small machine having the greatest possible 
radius of action. Frontiers would be no barrier to it. 
Sent from England in the night it could hover over a Kiel 
canal or an island of Heligoland at sunrise, there to observe 
in most leisurely fashion an enemy's mobilizations. 

At the London meeting of the Institute of Naval Archi- 
tects, in April, 191 1, the opinion was expressed that the only 
effective way of meeting attack from a flying machine at 
sea would be by a counter-attack from the same type of 
craft. The ship designers concluded that the aeroplane 
would no more limit the sizes of battleships than the 
torpedo has limited them. 

For the more serious work of fighting, larger balloons 
would be needed, with net carrying capacities perhaps 
upward from one ton. Such a machine could launch 
explosives and combustibles against the enemy's forts, dry 
docks, arsenals, magazines, and battleships. It could easily 
and completely destroy his railroads and bridges; perhaps 
even his capital itself, including the buildings housing his 
chief executive and war office staff. Nothing — it would 
seem — could effectually combat it save air craft of its own 
kind. The battles of the future may be battles of the air. 

There are of course difficulties in the way of dropping 
missiles of any great size from flying machines. Curtiss 
and others have shown that accuracy of aim is possible. 
Eight-pound shrapnel shells have been dropped from an 



Aerial Warfare 



199 




Santos-Dumont Circling the Eiffel Tower 
(From Walker's Aerial Navigation) 



200 Flying Machines Today 

aeroplane with measurably good effect, without upsetting 
the vessel; but at best the sudden liberation of a consider- 
able weight will introduce stabilizing and controlling diffi- 
culties. The passengers who made junketing trips about 
Paris on the Clement-Bayard complained that they were 
not allowed to throw even a chicken-bone overboard! But 
it does not seem too much to expect that these purely 
mechanical difficulties will be overcome by purely mechan- 
ical remedies. An automatic venting of a gas ballonet 
of just sufficient size to compensate for the weight of the 
dropped shell would answer in a balloon: a similar auto- 
matic change in propeller speed and angle of planes would 
suffice with the aeroplane. There is no doubt but that 
air craft may be made efficient agents of destruction on a 
colossal scale. 

A Swedish engineer officer has invented an aerial tor- 
pedo, automatically propelled and balanced like an ordi- 
nary submarine torpedo. It is stated to have an effective 
radius of three miles while carrying two and one-half 
pounds of explosive at the speed of a bullet. One can see 
no reason why such torpedoes of the largest size are not 
entirely practicable: though much lower speeds than that 
stated should be sufficient. 

According to press reports, the Krupps have developed 
a non-recoiling torpedo, having a range exceeding 5000 
yards. The percussion device is locked at the start, to 
prevent premature explosion: unlocking occurs only after 
a certain velocity has been attained. 



Aerial Warfare 201 

Major Squier apparently contends that the prohibition 
of offensive aerial operations is unfair, unless with it 
there goes the reciprocal provision that a war balloon 
shall not be fired at from below. Again, there seems 
to be no good reason why aerial mines dropped from 
above should be forbidden, while submarine mines — 
the most dangerous naval weapons — are allowed. Mod- 
ern strategy aims to capture rather than to destroy: 
the manceuvering of the enemy into untenable situations 
by the rapid mobilization of troops being the end of 
present-day highly organized staffs. Whether the dirigi- 
ble (certainly not the aeroplane) will ever become an 
effective vehicle for transport of large bodies of troops 
cannot yet be foreseen. 

Differences in national temper and tradition, and the 
conflict of commercial enterprise, perhaps the very recent- 
ness of the growth of a spirit of national unity on the one 
hand, are rapidly bringing the two foremost powers of 
Europe into keen competition: a competition which is 
resulting in a bloodless revolution in England, necessitated 
by the financial requirements of its naval program. Ger- 
many, by its strategic geographical position, its dominating 
military organization, and the enforced frugality, resource- 
fulness, and efficiency of its people, possesses what must 
be regarded as the most invincible army in the world. Its 
avowed purpose is an equally invincible navy. Whether 
the Gibraltar-Power can keep its ascendancy may well 
be doubted. The one doubtful — and at the same time 



202 



Flying Machines Today 



perhaps hopeful — factor lies in the possibilities of aerial 
navigation. 

If one battleship, in terms of dollars, represents 16,000 
airships, and if one or a dozen of the latter can destroy the 




Latham, Farman, and Paulhan 



former — a feat not perhaps beyond the bounds of pos- 
sibility — if the fortress that represents the skill and labor 
of generations may be razed by twoscore men operating 
from aloft, then the nations may beat their spears into 
pruning-hooks and their swords into plowshares: then the 



Aerial Warfare 203 

battle ceases to hinge on the power of the purse. Let 
war be made so costly that nations can no more afford it 
than sane men can wrestle on the brink of a precipice. 
Let armed international strife be viewed as it really is 

— senseless as the now dying duello. Let the navy that 
represents the wealth, the best engineering, the highest 
courage and skill, of our age, be powerless at the attack of 
a swarm of trifling gnats like Gulliver bound by Lilliputians 

— what happens then? It is a reductio ad absurdum. 
Destructive war becomes so superlatively destructive as to 
destroy itself. 

There is only one other way. Let the two rival 
Powers on whom the peace of the world depends set- 
tle their difficulties — surely the earth must be big 
enough for both! — and then as one' would gently but 
firmly take away from a small boy his too destructive 
toy rifle, spike the guns and scuttle the ships, their own 
and all the rest, leaving to some unambitious and neutral 
power the prosaic task of policing the world. Here is a 
work for red blood and national self-consciousness. If 
war were ever needed for man's best development, other 
things will answer now. The torn bodies and desolated 
homes of millions of men have paid the price demanded. 
Xo imaged hell can surpass the unnamed horrors that 
our fathers braved. 

" Enforced disarmament!'' Why not? Force (and pub- 
lic opinion) have abolished private duels. Why not na- 
tional duels as well? Civilization's control of savagery 



204 



Flying Machines Today 



always begins with compulsion. For a generation, no 
first-class power has had home experience in a serious 
armed conflict. We should not willingly contemplate 
such experience now. We have too much to do in the world 
to fight. 



The writer has felt some hesitancy in letting these words 
stand as the conclusion of a book on flying machines: but 
as with the old Roman who terminated every oration with 
a defiance of Carthage, the conviction prevails that no 
other question of the day is of comparable importance; 
and on a matter of overwhelming consequence like this no 
word can ever be out of place. The five chief powers spent 
for war purposes (officially, as Professor Johnson puts it, 
for the " preservation of peace") about $1,000,000,000 in the 
year 1908. In the worst period of the Napoleonic opera- 
tions the French military and naval budget was less than 
$100,000,000 annually. Great Britain, on the present peace 
footing, is spending for armament more rapidly than from 
1793 to 181 5. The gigantic "War of the Spanish Succes- 
sion" (which changed the map of Europe) cost England less 
than a present year's military expenditure. Since the 
types for these pages have been set, the promise of interna- 
tional peace has been distinctly strengthened. President 
Taft has suggested that as, first, questions of individual 
privilege, and, finally, even those of individual honor, have 
been by common consent submitted to adjudication, so 
also may those so-called " issues involving national honor" 



Aerial Warfare 205 

be disposed of without dishonor by international arbitration. 
Sir Edward Grey, who does not hesitate to say that increase 
of armaments may end in the destruction of civilization 
unless stopped by revolt of the masses against the increas- 
ing burdens of taxation, has electrified Europe by his recep- 
tion of the Taft pronouncement. England and the United 
States rule one-third the inhabitants of the earth. It is 
true that a defensive alliance might be more advantageous 
to the former and disagreeably entangling to the latter; 
but a binding treaty of arbitration between these powers 
would nevertheless be a worthy climax to our present era. 
And if it led to alliance against a third nation which had 
refused to arbitrate (led — - as Sir Edward Grey suggests 
— by the logic of events and not by subterranean device) 
would not such be the fitting and conclusive outcome? 

The Taft- Grey program — one would wish to call it 
that — has had all reputable endorsement; in England, 
no factional opposition may be expected. Our own jingoes 
are strangely silent. Mr. Dillon's fear that compulsory 
disarmament would militate against the weaker nations is 
offset by the hearty adherence of Denmark. A resolution 
in favor of the establishment of an international police force 
has passed the House of Commons by a heavy majority. 
It looks now as if we might hope before long to re-date our 
centuries. We have had Olympiads and Years of Rome, 
B.C. and a.d. Perhaps next the dream of thoughtful 
men may find its realization in the new (and, we may 
hope, English) prefix, Y.P. — Year of Peace. 



Books on Aeronautics 



FLYING MACHINES TO-DA Y. By WILLIAM D. ENNIS, M. E., Professor 
of Mechanical Engineering, Polytechnic Institute, Brooklyn. 

i2mo., cloth, 218 pp., 123 illustrations $1.50 net 

CONTENTS : The Delights and Dangers of Flying— Dangers of Aviation— What 
it is Like to Fly. Soaking Flight bt Man— What Holds it Up. Lifting Power. Why 
so Many Sails. Steering. Turning Corners— What Happens When Making a Turn. 
Lateral Stability. Wing Warping. Automatic Control. The Gyroscope. Wind Gusts. 
Air and the Wind— Sailing Balloons. Field and Speed. Gas and Ballast — 
Buoyancy in Air. Ascending and Descending. The Ballonet. The Equilibrator. 
Dirigible Balloons and Other Kinds— Shapes. Dimensions. Fabrics. Framing. 
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Some Accomplishments. The Possibilities in Aviation— Case of the Dirigible. The 
Orthopter. The Helicopter. Composite Types. What is Promised. Aerial Warfare. 

AERIAL FLIGHT. Vol. I. Aerodynamics. By F. W. LANCHESTER. 
8vo., cloth, 438 pp., 162 illustrations : $6.00 net 

CONTENTS : Fluid Resistance and Its Associated Phenomena. Viscosity and Skin 
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Vol. II. Aerodonetics. By F. W. LANCHESTER. 
8vo., cloth, 433 pp., 208 illustrations $6.00 net 

CONTENTS: Free Flight, General Principles and Phenomena. The Phugoid 
Theory— The Equations of the Flight Path. The Phugoid 1852-1872. Dirigible 
Balloons from 1883-1897; 1898-1906. Flying Machine Theory— The Flight Path 
Plotted. Elementary Deductions from the Phugoid Theory. Stability of the Flight 
Path as Affected by Resistance and Moment of Inertia. Experimental Evidence 
and Verification of the Phugoid Theory. Lateral and Directional Stability. Review of 
Chapters I to VII, and General Conclusions. Soaring. Experimental. Aerodonetics. 

AERIAL NAVIGATION. A practical handbook on the construction 
of dirigible balloons, aerostats, aeroplanes and aeromotors, by 

FREDERICK WALKER. 12mo., cloth, 151 PP ., 100 illustrations. .$3.00 net 

CONTENTS: Laws of Flight. Aerostatics. Aerostats. Aerodynamics. Screw 
Propulsion. Paddles and Aeroplanes. Motive Power. Structure of Air-Ships and 
Materials. Air Ships. Appendix. 

AEROPLANE PATENTS. By ROBERT M. NEILSON. 8vo., cloth, 101 

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CONTENTS: Advice to Inventors. Review of British Patents. British Patents and 
Applications for Pateuts from 1860 to 1910, Arranged in Order of Application. British 
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in Order of Issue. United States Patentees, Arranged Alphabetically. 

(over) 



THE PRINCIPLES OF AEROPLANE CONSTRUCTION. By RANKIN 
KENNEDY, C E. 8vo., cloth, 145 pp., 51 diagrams $1.50 net 

CONTENTS : Elementary Mechanics and Physics. Principles of Inclined Planes. 
Air and Its Properties. Principles of the Aeroplane. The Curves of the Aeroplane. 
Centers of Gravity: Balancing; Steering. The Propeller. The Helicoptere. The Wing 
Propeller. The Engine. The Future of the Aeroplane. 

HOW TO DESIGN AN AEROPLANE. By HERBERT CHATLEY. 

16mo., boards, 109 pp., illustrated (Van Nostrand's Science Series). . . .50 cents 

CONTENTS : The Aeroplane. Air Pressure. Weight. Propellers and Motors. 
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Machines (Gyroplane and Orinthoptere). 

HOW TO BUILD AN AEROPLANE. By ROBERT PETIT. Translated 

from the French by T. O'B. Hubbard and J. H. Ledeboer. 8vo., cloth, 131 pp., 
93 illustrations . .. $1.50 net 

CONTENTS : General Principles of Aeroplane Design. Theory and Calculation. 
Resistance, Lift, Power, Calculations for the Design of an Aeroplane, Application of 
Power, Design of Propeller, Arrangements of Surfaces, Stability, Center of Gravity, etc. 
Materials. Construction of Propellers. Arrangements for Starting and Landing. Controls. 
Placing Motor. The Planes. Curvatures. Motors. 

AIRSHIPS, PAST AND PRESENT. Together with chapters on the 
use of balloons in connection with meteorology, photography, 
and the carrier pigeon. By A. HILDEBRANDT, Captain and Instructor 

in the Prussian Balloon Corps. Translated by W. H. Story. 8vo., cloth, 36 1 pp., 
222 illustrations $3.50 net 

CONTENTS : Early History of the Art. Invention of the Air Balloon. Montgolfieres, 
Charlieres, and Rozieres. Theory of the Balloon. Development of the Dirigible Bal- 
loon. History of the Dirigible Balloon, 1852-1872. Dirigible Balloons from 1883-1897; 
1898-1906. Flying Machines. Kites. Parachutes. Development of Military Ballooning. 
Ballooning in Franco-Prussian War. Modern Organization of Military Ballooning in 
France, Germany, England and Russia. Military Ballooning in Other Countries. Balloon 
Construction and the Preparation of the Gas. Instruments. Ballooning as a Sport. 
Scientific Ballooning. Balloon Photography. Photographic Outfit for Balloon Work. 
Interpretation of Photographs. Hectography by Means of Kites and Rockets. Carrier 
Pigeons for Balloons. Balloon Law. 




D. VAN NOSTRAND CO., Publishers 

23 MURRAY and 27 WARREN STREETS, NEW YORK 



AUG 16 1911 



One copy del. to Cat. Div. 



AUG t§ 1911 



